Merge subscriptions into master

51 files changed, 12341 insertions, 0 deletions

diff --git a/python/atoma/__init__.py b/python/atoma/__init__.py
new file mode 100644
index 0000000..0768081
--- /dev/null
+++ b/python/atoma/__init__.py
@@ -0,0 +1,12 @@
+from .atom import parse_atom_file, parse_atom_bytes
+from .rss import parse_rss_file, parse_rss_bytes
+from .json_feed import (
+    parse_json_feed, parse_json_feed_file, parse_json_feed_bytes
+)
+from .opml import parse_opml_file, parse_opml_bytes
+from .exceptions import (
+    FeedParseError, FeedDocumentError, FeedXMLError, FeedJSONError
+)
+from .const import VERSION
+
+__version__ = VERSION
diff --git a/python/atoma/atom.py b/python/atoma/atom.py
new file mode 100644
index 0000000..d4e676c
--- /dev/null
+++ b/python/atoma/atom.py
@@ -0,0 +1,284 @@
+from datetime import datetime
+import enum
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import (
+    parse_xml, get_child, get_text, get_datetime, FeedParseError, ns
+)
+
+
+class AtomTextType(enum.Enum):
+    text = "text"
+    html = "html"
+    xhtml = "xhtml"
+
+
+@attr.s
+class AtomTextConstruct:
+    text_type: str = attr.ib()
+    lang: Optional[str] = attr.ib()
+    value: str = attr.ib()
+
+
+@attr.s
+class AtomEntry:
+    title: AtomTextConstruct = attr.ib()
+    id_: str = attr.ib()
+
+    # Should be mandatory but many feeds use published instead
+    updated: Optional[datetime] = attr.ib()
+
+    authors: List['AtomPerson'] = attr.ib()
+    contributors: List['AtomPerson'] = attr.ib()
+    links: List['AtomLink'] = attr.ib()
+    categories: List['AtomCategory'] = attr.ib()
+    published: Optional[datetime] = attr.ib()
+    rights: Optional[AtomTextConstruct] = attr.ib()
+    summary: Optional[AtomTextConstruct] = attr.ib()
+    content: Optional[AtomTextConstruct] = attr.ib()
+    source: Optional['AtomFeed'] = attr.ib()
+
+
+@attr.s
+class AtomFeed:
+    title: Optional[AtomTextConstruct] = attr.ib()
+    id_: str = attr.ib()
+
+    # Should be mandatory but many feeds do not include it
+    updated: Optional[datetime] = attr.ib()
+
+    authors: List['AtomPerson'] = attr.ib()
+    contributors: List['AtomPerson'] = attr.ib()
+    links: List['AtomLink'] = attr.ib()
+    categories: List['AtomCategory'] = attr.ib()
+    generator: Optional['AtomGenerator'] = attr.ib()
+    subtitle: Optional[AtomTextConstruct] = attr.ib()
+    rights: Optional[AtomTextConstruct] = attr.ib()
+    icon: Optional[str] = attr.ib()
+    logo: Optional[str] = attr.ib()
+
+    entries: List[AtomEntry] = attr.ib()
+
+
+@attr.s
+class AtomPerson:
+    name: str = attr.ib()
+    uri: Optional[str] = attr.ib()
+    email: Optional[str] = attr.ib()
+
+
+@attr.s
+class AtomLink:
+    href: str = attr.ib()
+    rel: Optional[str] = attr.ib()
+    type_: Optional[str] = attr.ib()
+    hreflang: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    length: Optional[int] = attr.ib()
+
+
+@attr.s
+class AtomCategory:
+    term: str = attr.ib()
+    scheme: Optional[str] = attr.ib()
+    label: Optional[str] = attr.ib()
+
+
+@attr.s
+class AtomGenerator:
+    name: str = attr.ib()
+    uri: Optional[str] = attr.ib()
+    version: Optional[str] = attr.ib()
+
+
+def _get_generator(element: Element, name,
+                   optional: bool=True) -> Optional[AtomGenerator]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return AtomGenerator(
+        child.text.strip(),
+        child.attrib.get('uri'),
+        child.attrib.get('version'),
+    )
+
+
+def _get_text_construct(element: Element, name,
+                        optional: bool=True) -> Optional[AtomTextConstruct]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    try:
+        text_type = AtomTextType(child.attrib['type'])
+    except KeyError:
+        text_type = AtomTextType.text
+
+    try:
+        lang = child.lang
+    except AttributeError:
+        lang = None
+
+    if child.text is None:
+        if optional:
+            return None
+
+        raise FeedParseError(
+            'Could not parse atom feed: "{}" text is required but is empty'
+            .format(name)
+        )
+
+    return AtomTextConstruct(
+        text_type,
+        lang,
+        child.text.strip()
+    )
+
+
+def _get_person(element: Element) -> Optional[AtomPerson]:
+    try:
+        return AtomPerson(
+            get_text(element, 'feed:name', optional=False),
+            get_text(element, 'feed:uri'),
+            get_text(element, 'feed:email')
+        )
+    except FeedParseError:
+        return None
+
+
+def _get_link(element: Element) -> AtomLink:
+    length = element.attrib.get('length')
+    length = int(length) if length else None
+    return AtomLink(
+        element.attrib['href'],
+        element.attrib.get('rel'),
+        element.attrib.get('type'),
+        element.attrib.get('hreflang'),
+        element.attrib.get('title'),
+        length
+    )
+
+
+def _get_category(element: Element) -> AtomCategory:
+    return AtomCategory(
+        element.attrib['term'],
+        element.attrib.get('scheme'),
+        element.attrib.get('label'),
+    )
+
+
+def _get_entry(element: Element,
+               default_authors: List[AtomPerson]) -> AtomEntry:
+    root = element
+
+    # Mandatory
+    title = _get_text_construct(root, 'feed:title')
+    id_ = get_text(root, 'feed:id')
+
+    # Optional
+    try:
+        source = _parse_atom(get_child(root, 'feed:source', optional=False),
+                             parse_entries=False)
+    except FeedParseError:
+        source = None
+        source_authors = []
+    else:
+        source_authors = source.authors
+
+    authors = [_get_person(e)
+               for e in root.findall('feed:author', ns)] or default_authors
+    authors = [a for a in authors if a is not None]
+    authors = authors or default_authors or source_authors
+
+    contributors = [_get_person(e)
+                    for e in root.findall('feed:contributor', ns) if e]
+    contributors = [c for c in contributors if c is not None]
+
+    links = [_get_link(e) for e in root.findall('feed:link', ns)]
+    categories = [_get_category(e) for e in root.findall('feed:category', ns)]
+
+    updated = get_datetime(root, 'feed:updated')
+    published = get_datetime(root, 'feed:published')
+    rights = _get_text_construct(root, 'feed:rights')
+    summary = _get_text_construct(root, 'feed:summary')
+    content = _get_text_construct(root, 'feed:content')
+
+    return AtomEntry(
+        title,
+        id_,
+        updated,
+        authors,
+        contributors,
+        links,
+        categories,
+        published,
+        rights,
+        summary,
+        content,
+        source
+    )
+
+
+def _parse_atom(root: Element, parse_entries: bool=True) -> AtomFeed:
+    # Mandatory
+    id_ = get_text(root, 'feed:id', optional=False)
+
+    # Optional
+    title = _get_text_construct(root, 'feed:title')
+    updated = get_datetime(root, 'feed:updated')
+    authors = [_get_person(e)
+               for e in root.findall('feed:author', ns) if e]
+    authors = [a for a in authors if a is not None]
+    contributors = [_get_person(e)
+                    for e in root.findall('feed:contributor', ns) if e]
+    contributors = [c for c in contributors if c is not None]
+    links = [_get_link(e)
+             for e in root.findall('feed:link', ns)]
+    categories = [_get_category(e)
+                  for e in root.findall('feed:category', ns)]
+
+    generator = _get_generator(root, 'feed:generator')
+    subtitle = _get_text_construct(root, 'feed:subtitle')
+    rights = _get_text_construct(root, 'feed:rights')
+    icon = get_text(root, 'feed:icon')
+    logo = get_text(root, 'feed:logo')
+
+    if parse_entries:
+        entries = [_get_entry(e, authors)
+                   for e in root.findall('feed:entry', ns)]
+    else:
+        entries = []
+
+    atom_feed = AtomFeed(
+        title,
+        id_,
+        updated,
+        authors,
+        contributors,
+        links,
+        categories,
+        generator,
+        subtitle,
+        rights,
+        icon,
+        logo,
+        entries
+    )
+    return atom_feed
+
+
+def parse_atom_file(filename: str) -> AtomFeed:
+    """Parse an Atom feed from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_atom(root)
+
+
+def parse_atom_bytes(data: bytes) -> AtomFeed:
+    """Parse an Atom feed from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_atom(root)
diff --git a/python/atoma/const.py b/python/atoma/const.py
new file mode 100644
index 0000000..d52d0f6
--- /dev/null
+++ b/python/atoma/const.py
@@ -0,0 +1 @@
+VERSION = '0.0.13'
diff --git a/python/atoma/exceptions.py b/python/atoma/exceptions.py
new file mode 100644
index 0000000..88170c5
--- /dev/null
+++ b/python/atoma/exceptions.py
@@ -0,0 +1,14 @@
+class FeedParseError(Exception):
+    """Document is an invalid feed."""
+
+
+class FeedDocumentError(Exception):
+    """Document is not a supported file."""
+
+
+class FeedXMLError(FeedDocumentError):
+    """Document is not valid XML."""
+
+
+class FeedJSONError(FeedDocumentError):
+    """Document is not valid JSON."""
diff --git a/python/atoma/json_feed.py b/python/atoma/json_feed.py
new file mode 100644
index 0000000..410ff4a
--- /dev/null
+++ b/python/atoma/json_feed.py
@@ -0,0 +1,223 @@
+from datetime import datetime, timedelta
+import json
+from typing import Optional, List
+
+import attr
+
+from .exceptions import FeedParseError, FeedJSONError
+from .utils import try_parse_date
+
+
+@attr.s
+class JSONFeedAuthor:
+
+    name: Optional[str] = attr.ib()
+    url: Optional[str] = attr.ib()
+    avatar: Optional[str] = attr.ib()
+
+
+@attr.s
+class JSONFeedAttachment:
+
+    url: str = attr.ib()
+    mime_type: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    size_in_bytes: Optional[int] = attr.ib()
+    duration: Optional[timedelta] = attr.ib()
+
+
+@attr.s
+class JSONFeedItem:
+
+    id_: str = attr.ib()
+    url: Optional[str] = attr.ib()
+    external_url: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    content_html: Optional[str] = attr.ib()
+    content_text: Optional[str] = attr.ib()
+    summary: Optional[str] = attr.ib()
+    image: Optional[str] = attr.ib()
+    banner_image: Optional[str] = attr.ib()
+    date_published: Optional[datetime] = attr.ib()
+    date_modified: Optional[datetime] = attr.ib()
+    author: Optional[JSONFeedAuthor] = attr.ib()
+
+    tags: List[str] = attr.ib()
+    attachments: List[JSONFeedAttachment] = attr.ib()
+
+
+@attr.s
+class JSONFeed:
+
+    version: str = attr.ib()
+    title: str = attr.ib()
+    home_page_url: Optional[str] = attr.ib()
+    feed_url: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    user_comment: Optional[str] = attr.ib()
+    next_url: Optional[str] = attr.ib()
+    icon: Optional[str] = attr.ib()
+    favicon: Optional[str] = attr.ib()
+    author: Optional[JSONFeedAuthor] = attr.ib()
+    expired: bool = attr.ib()
+
+    items: List[JSONFeedItem] = attr.ib()
+
+
+def _get_items(root: dict) -> List[JSONFeedItem]:
+    rv = []
+    items = root.get('items', [])
+    if not items:
+        return rv
+
+    for item in items:
+        rv.append(_get_item(item))
+
+    return rv
+
+
+def _get_item(item_dict: dict) -> JSONFeedItem:
+    return JSONFeedItem(
+        id_=_get_text(item_dict, 'id', optional=False),
+        url=_get_text(item_dict, 'url'),
+        external_url=_get_text(item_dict, 'external_url'),
+        title=_get_text(item_dict, 'title'),
+        content_html=_get_text(item_dict, 'content_html'),
+        content_text=_get_text(item_dict, 'content_text'),
+        summary=_get_text(item_dict, 'summary'),
+        image=_get_text(item_dict, 'image'),
+        banner_image=_get_text(item_dict, 'banner_image'),
+        date_published=_get_datetime(item_dict, 'date_published'),
+        date_modified=_get_datetime(item_dict, 'date_modified'),
+        author=_get_author(item_dict),
+        tags=_get_tags(item_dict, 'tags'),
+        attachments=_get_attachments(item_dict, 'attachments')
+    )
+
+
+def _get_attachments(root, name) -> List[JSONFeedAttachment]:
+    rv = list()
+    for attachment_dict in root.get(name, []):
+        rv.append(JSONFeedAttachment(
+            _get_text(attachment_dict, 'url', optional=False),
+            _get_text(attachment_dict, 'mime_type', optional=False),
+            _get_text(attachment_dict, 'title'),
+            _get_int(attachment_dict, 'size_in_bytes'),
+            _get_duration(attachment_dict, 'duration_in_seconds')
+        ))
+    return rv
+
+
+def _get_tags(root, name) -> List[str]:
+    tags = root.get(name, [])
+    return [tag for tag in tags if isinstance(tag, str)]
+
+
+def _get_datetime(root: dict, name, optional: bool=True) -> Optional[datetime]:
+    text = _get_text(root, name, optional)
+    if text is None:
+        return None
+
+    return try_parse_date(text)
+
+
+def _get_expired(root: dict) -> bool:
+    if root.get('expired') is True:
+        return True
+
+    return False
+
+
+def _get_author(root: dict) -> Optional[JSONFeedAuthor]:
+    author_dict = root.get('author')
+    if not author_dict:
+        return None
+
+    rv = JSONFeedAuthor(
+        name=_get_text(author_dict, 'name'),
+        url=_get_text(author_dict, 'url'),
+        avatar=_get_text(author_dict, 'avatar'),
+    )
+    if rv.name is None and rv.url is None and rv.avatar is None:
+        return None
+
+    return rv
+
+
+def _get_int(root: dict, name: str, optional: bool=True) -> Optional[int]:
+    rv = root.get(name)
+    if not optional and rv is None:
+        raise FeedParseError('Could not parse feed: "{}" int is required but '
+                             'is empty'.format(name))
+
+    if optional and rv is None:
+        return None
+
+    if not isinstance(rv, int):
+        raise FeedParseError('Could not parse feed: "{}" is not an int'
+                             .format(name))
+
+    return rv
+
+
+def _get_duration(root: dict, name: str,
+                  optional: bool=True) -> Optional[timedelta]:
+    duration = _get_int(root, name, optional)
+    if duration is None:
+        return None
+
+    return timedelta(seconds=duration)
+
+
+def _get_text(root: dict, name: str, optional: bool=True) -> Optional[str]:
+    rv = root.get(name)
+    if not optional and rv is None:
+        raise FeedParseError('Could not parse feed: "{}" text is required but '
+                             'is empty'.format(name))
+
+    if optional and rv is None:
+        return None
+
+    if not isinstance(rv, str):
+        raise FeedParseError('Could not parse feed: "{}" is not a string'
+                             .format(name))
+
+    return rv
+
+
+def parse_json_feed(root: dict) -> JSONFeed:
+    return JSONFeed(
+        version=_get_text(root, 'version', optional=False),
+        title=_get_text(root, 'title', optional=False),
+        home_page_url=_get_text(root, 'home_page_url'),
+        feed_url=_get_text(root, 'feed_url'),
+        description=_get_text(root, 'description'),
+        user_comment=_get_text(root, 'user_comment'),
+        next_url=_get_text(root, 'next_url'),
+        icon=_get_text(root, 'icon'),
+        favicon=_get_text(root, 'favicon'),
+        author=_get_author(root),
+        expired=_get_expired(root),
+        items=_get_items(root)
+    )
+
+
+def parse_json_feed_file(filename: str) -> JSONFeed:
+    """Parse a JSON feed from a local json file."""
+    with open(filename) as f:
+        try:
+            root = json.load(f)
+        except json.decoder.JSONDecodeError:
+            raise FeedJSONError('Not a valid JSON document')
+
+    return parse_json_feed(root)
+
+
+def parse_json_feed_bytes(data: bytes) -> JSONFeed:
+    """Parse a JSON feed from a byte-string containing JSON data."""
+    try:
+        root = json.loads(data)
+    except json.decoder.JSONDecodeError:
+        raise FeedJSONError('Not a valid JSON document')
+
+    return parse_json_feed(root)
diff --git a/python/atoma/opml.py b/python/atoma/opml.py
new file mode 100644
index 0000000..a73105e
--- /dev/null
+++ b/python/atoma/opml.py
@@ -0,0 +1,107 @@
+from datetime import datetime
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import parse_xml, get_text, get_int, get_datetime
+
+
+@attr.s
+class OPMLOutline:
+    text: Optional[str] = attr.ib()
+    type: Optional[str] = attr.ib()
+    xml_url: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    html_url: Optional[str] = attr.ib()
+    language: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    version: Optional[str] = attr.ib()
+
+    outlines: List['OPMLOutline'] = attr.ib()
+
+
+@attr.s
+class OPML:
+    title: Optional[str] = attr.ib()
+    owner_name: Optional[str] = attr.ib()
+    owner_email: Optional[str] = attr.ib()
+    date_created: Optional[datetime] = attr.ib()
+    date_modified: Optional[datetime] = attr.ib()
+    expansion_state: Optional[str] = attr.ib()
+
+    vertical_scroll_state: Optional[int] = attr.ib()
+    window_top: Optional[int] = attr.ib()
+    window_left: Optional[int] = attr.ib()
+    window_bottom: Optional[int] = attr.ib()
+    window_right: Optional[int] = attr.ib()
+
+    outlines: List[OPMLOutline] = attr.ib()
+
+
+def _get_outlines(element: Element) -> List[OPMLOutline]:
+    rv = list()
+
+    for outline in element.findall('outline'):
+        rv.append(OPMLOutline(
+            outline.attrib.get('text'),
+            outline.attrib.get('type'),
+            outline.attrib.get('xmlUrl'),
+            outline.attrib.get('description'),
+            outline.attrib.get('htmlUrl'),
+            outline.attrib.get('language'),
+            outline.attrib.get('title'),
+            outline.attrib.get('version'),
+            _get_outlines(outline)
+        ))
+
+    return rv
+
+
+def _parse_opml(root: Element) -> OPML:
+    head = root.find('head')
+    body = root.find('body')
+
+    return OPML(
+        get_text(head, 'title'),
+        get_text(head, 'ownerName'),
+        get_text(head, 'ownerEmail'),
+        get_datetime(head, 'dateCreated'),
+        get_datetime(head, 'dateModified'),
+        get_text(head, 'expansionState'),
+        get_int(head, 'vertScrollState'),
+        get_int(head, 'windowTop'),
+        get_int(head, 'windowLeft'),
+        get_int(head, 'windowBottom'),
+        get_int(head, 'windowRight'),
+        outlines=_get_outlines(body)
+    )
+
+
+def parse_opml_file(filename: str) -> OPML:
+    """Parse an OPML document from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_opml(root)
+
+
+def parse_opml_bytes(data: bytes) -> OPML:
+    """Parse an OPML document from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_opml(root)
+
+
+def get_feed_list(opml_obj: OPML) -> List[str]:
+    """Walk an OPML document to extract the list of feed it contains."""
+    rv = list()
+
+    def collect(obj):
+        for outline in obj.outlines:
+            if outline.type == 'rss' and outline.xml_url:
+                rv.append(outline.xml_url)
+
+            if outline.outlines:
+                collect(outline)
+
+    collect(opml_obj)
+    return rv
diff --git a/python/atoma/rss.py b/python/atoma/rss.py
new file mode 100644
index 0000000..f447a2f
--- /dev/null
+++ b/python/atoma/rss.py
@@ -0,0 +1,221 @@
+from datetime import datetime
+from io import BytesIO
+from typing import Optional, List
+from xml.etree.ElementTree import Element
+
+import attr
+
+from .utils import (
+    parse_xml, get_child, get_text, get_int, get_datetime, FeedParseError
+)
+
+
+@attr.s
+class RSSImage:
+    url: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    link: str = attr.ib()
+    width: int = attr.ib()
+    height: int = attr.ib()
+    description: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSEnclosure:
+    url: str = attr.ib()
+    length: Optional[int] = attr.ib()
+    type: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSSource:
+    title: str = attr.ib()
+    url: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSItem:
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    author: Optional[str] = attr.ib()
+    categories: List[str] = attr.ib()
+    comments: Optional[str] = attr.ib()
+    enclosures: List[RSSEnclosure] = attr.ib()
+    guid: Optional[str] = attr.ib()
+    pub_date: Optional[datetime] = attr.ib()
+    source: Optional[RSSSource] = attr.ib()
+
+    # Extension
+    content_encoded: Optional[str] = attr.ib()
+
+
+@attr.s
+class RSSChannel:
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    description: Optional[str] = attr.ib()
+    language: Optional[str] = attr.ib()
+    copyright: Optional[str] = attr.ib()
+    managing_editor: Optional[str] = attr.ib()
+    web_master: Optional[str] = attr.ib()
+    pub_date: Optional[datetime] = attr.ib()
+    last_build_date: Optional[datetime] = attr.ib()
+    categories: List[str] = attr.ib()
+    generator: Optional[str] = attr.ib()
+    docs: Optional[str] = attr.ib()
+    ttl: Optional[int] = attr.ib()
+    image: Optional[RSSImage] = attr.ib()
+
+    items: List[RSSItem] = attr.ib()
+
+    # Extension
+    content_encoded: Optional[str] = attr.ib()
+
+
+def _get_image(element: Element, name,
+               optional: bool=True) -> Optional[RSSImage]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return RSSImage(
+        get_text(child, 'url', optional=False),
+        get_text(child, 'title'),
+        get_text(child, 'link', optional=False),
+        get_int(child, 'width') or 88,
+        get_int(child, 'height') or 31,
+        get_text(child, 'description')
+    )
+
+
+def _get_source(element: Element, name,
+                optional: bool=True) -> Optional[RSSSource]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    return RSSSource(
+        child.text.strip(),
+        child.attrib.get('url'),
+    )
+
+
+def _get_enclosure(element: Element) -> RSSEnclosure:
+    length = element.attrib.get('length')
+    try:
+        length = int(length)
+    except (TypeError, ValueError):
+        length = None
+
+    return RSSEnclosure(
+        element.attrib['url'],
+        length,
+        element.attrib.get('type'),
+    )
+
+
+def _get_link(element: Element) -> Optional[str]:
+    """Attempt to retrieve item link.
+
+    Use the GUID as a fallback if it is a permalink.
+    """
+    link = get_text(element, 'link')
+    if link is not None:
+        return link
+
+    guid = get_child(element, 'guid')
+    if guid is not None and guid.attrib.get('isPermaLink') == 'true':
+        return get_text(element, 'guid')
+
+    return None
+
+
+def _get_item(element: Element) -> RSSItem:
+    root = element
+
+    title = get_text(root, 'title')
+    link = _get_link(root)
+    description = get_text(root, 'description')
+    author = get_text(root, 'author')
+    categories = [e.text for e in root.findall('category')]
+    comments = get_text(root, 'comments')
+    enclosure = [_get_enclosure(e) for e in root.findall('enclosure')]
+    guid = get_text(root, 'guid')
+    pub_date = get_datetime(root, 'pubDate')
+    source = _get_source(root, 'source')
+
+    content_encoded = get_text(root, 'content:encoded')
+
+    return RSSItem(
+        title,
+        link,
+        description,
+        author,
+        categories,
+        comments,
+        enclosure,
+        guid,
+        pub_date,
+        source,
+        content_encoded
+    )
+
+
+def _parse_rss(root: Element) -> RSSChannel:
+    rss_version = root.get('version')
+    if rss_version != '2.0':
+        raise FeedParseError('Cannot process RSS feed version "{}"'
+                             .format(rss_version))
+
+    root = root.find('channel')
+
+    title = get_text(root, 'title')
+    link = get_text(root, 'link')
+    description = get_text(root, 'description')
+    language = get_text(root, 'language')
+    copyright = get_text(root, 'copyright')
+    managing_editor = get_text(root, 'managingEditor')
+    web_master = get_text(root, 'webMaster')
+    pub_date = get_datetime(root, 'pubDate')
+    last_build_date = get_datetime(root, 'lastBuildDate')
+    categories = [e.text for e in root.findall('category')]
+    generator = get_text(root, 'generator')
+    docs = get_text(root, 'docs')
+    ttl = get_int(root, 'ttl')
+
+    image = _get_image(root, 'image')
+    items = [_get_item(e) for e in root.findall('item')]
+
+    content_encoded = get_text(root, 'content:encoded')
+
+    return RSSChannel(
+        title,
+        link,
+        description,
+        language,
+        copyright,
+        managing_editor,
+        web_master,
+        pub_date,
+        last_build_date,
+        categories,
+        generator,
+        docs,
+        ttl,
+        image,
+        items,
+        content_encoded
+    )
+
+
+def parse_rss_file(filename: str) -> RSSChannel:
+    """Parse an RSS feed from a local XML file."""
+    root = parse_xml(filename).getroot()
+    return _parse_rss(root)
+
+
+def parse_rss_bytes(data: bytes) -> RSSChannel:
+    """Parse an RSS feed from a byte-string containing XML data."""
+    root = parse_xml(BytesIO(data)).getroot()
+    return _parse_rss(root)
diff --git a/python/atoma/simple.py b/python/atoma/simple.py
new file mode 100644
index 0000000..98bb3e1
--- /dev/null
+++ b/python/atoma/simple.py
@@ -0,0 +1,224 @@
+"""Simple API that abstracts away the differences between feed types."""
+
+from datetime import datetime, timedelta
+import html
+import os
+from typing import Optional, List, Tuple
+import urllib.parse
+
+import attr
+
+from . import atom, rss, json_feed
+from .exceptions import (
+    FeedParseError, FeedDocumentError, FeedXMLError, FeedJSONError
+)
+
+
+@attr.s
+class Attachment:
+    link: str = attr.ib()
+    mime_type: Optional[str] = attr.ib()
+    title: Optional[str] = attr.ib()
+    size_in_bytes: Optional[int] = attr.ib()
+    duration: Optional[timedelta] = attr.ib()
+
+
+@attr.s
+class Article:
+    id: str = attr.ib()
+    title: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    content: str = attr.ib()
+    published_at: Optional[datetime] = attr.ib()
+    updated_at: Optional[datetime] = attr.ib()
+    attachments: List[Attachment] = attr.ib()
+
+
+@attr.s
+class Feed:
+    title: str = attr.ib()
+    subtitle: Optional[str] = attr.ib()
+    link: Optional[str] = attr.ib()
+    updated_at: Optional[datetime] = attr.ib()
+    articles: List[Article] = attr.ib()
+
+
+def _adapt_atom_feed(atom_feed: atom.AtomFeed) -> Feed:
+    articles = list()
+    for entry in atom_feed.entries:
+        if entry.content is not None:
+            content = entry.content.value
+        elif entry.summary is not None:
+            content = entry.summary.value
+        else:
+            content = ''
+        published_at, updated_at = _get_article_dates(entry.published,
+                                                      entry.updated)
+        # Find article link and attachments
+        article_link = None
+        attachments = list()
+        for candidate_link in entry.links:
+            if candidate_link.rel in ('alternate', None):
+                article_link = candidate_link.href
+            elif candidate_link.rel == 'enclosure':
+                attachments.append(Attachment(
+                    title=_get_attachment_title(candidate_link.title,
+                                                candidate_link.href),
+                    link=candidate_link.href,
+                    mime_type=candidate_link.type_,
+                    size_in_bytes=candidate_link.length,
+                    duration=None
+                ))
+
+        if entry.title is None:
+            entry_title = None
+        elif entry.title.text_type in (atom.AtomTextType.html,
+                                       atom.AtomTextType.xhtml):
+            entry_title = html.unescape(entry.title.value).strip()
+        else:
+            entry_title = entry.title.value
+
+        articles.append(Article(
+            entry.id_,
+            entry_title,
+            article_link,
+            content,
+            published_at,
+            updated_at,
+            attachments
+        ))
+
+    # Find feed link
+    link = None
+    for candidate_link in atom_feed.links:
+        if candidate_link.rel == 'self':
+            link = candidate_link.href
+            break
+
+    return Feed(
+        atom_feed.title.value if atom_feed.title else atom_feed.id_,
+        atom_feed.subtitle.value if atom_feed.subtitle else None,
+        link,
+        atom_feed.updated,
+        articles
+    )
+
+
+def _adapt_rss_channel(rss_channel: rss.RSSChannel) -> Feed:
+    articles = list()
+    for item in rss_channel.items:
+        attachments = [
+            Attachment(link=e.url, mime_type=e.type, size_in_bytes=e.length,
+                       title=_get_attachment_title(None, e.url), duration=None)
+            for e in item.enclosures
+        ]
+        articles.append(Article(
+            item.guid or item.link,
+            item.title,
+            item.link,
+            item.content_encoded or item.description or '',
+            item.pub_date,
+            None,
+            attachments
+        ))
+
+    if rss_channel.title is None and rss_channel.link is None:
+        raise FeedParseError('RSS feed does not have a title nor a link')
+
+    return Feed(
+        rss_channel.title if rss_channel.title else rss_channel.link,
+        rss_channel.description,
+        rss_channel.link,
+        rss_channel.pub_date,
+        articles
+    )
+
+
+def _adapt_json_feed(json_feed: json_feed.JSONFeed) -> Feed:
+    articles = list()
+    for item in json_feed.items:
+        attachments = [
+            Attachment(a.url, a.mime_type,
+                       _get_attachment_title(a.title, a.url),
+                       a.size_in_bytes, a.duration)
+            for a in item.attachments
+        ]
+        articles.append(Article(
+            item.id_,
+            item.title,
+            item.url,
+            item.content_html or item.content_text or '',
+            item.date_published,
+            item.date_modified,
+            attachments
+        ))
+
+    return Feed(
+        json_feed.title,
+        json_feed.description,
+        json_feed.feed_url,
+        None,
+        articles
+    )
+
+
+def _get_article_dates(published_at: Optional[datetime],
+                       updated_at: Optional[datetime]
+                       ) -> Tuple[Optional[datetime], Optional[datetime]]:
+    if published_at and updated_at:
+        return published_at, updated_at
+
+    if updated_at:
+        return updated_at, None
+
+    if published_at:
+        return published_at, None
+
+    raise FeedParseError('Article does not have proper dates')
+
+
+def _get_attachment_title(attachment_title: Optional[str], link: str) -> str:
+    if attachment_title:
+        return attachment_title
+
+    parsed_link = urllib.parse.urlparse(link)
+    return os.path.basename(parsed_link.path)
+
+
+def _simple_parse(pairs, content) -> Feed:
+    is_xml = True
+    is_json = True
+    for parser, adapter in pairs:
+        try:
+            return adapter(parser(content))
+        except FeedXMLError:
+            is_xml = False
+        except FeedJSONError:
+            is_json = False
+        except FeedParseError:
+            continue
+
+    if not is_xml and not is_json:
+        raise FeedDocumentError('File is not a supported feed type')
+
+    raise FeedParseError('File is not a valid supported feed')
+
+
+def simple_parse_file(filename: str) -> Feed:
+    """Parse an Atom, RSS or JSON feed from a local file."""
+    pairs = (
+        (rss.parse_rss_file, _adapt_rss_channel),
+        (atom.parse_atom_file, _adapt_atom_feed),
+        (json_feed.parse_json_feed_file, _adapt_json_feed)
+    )
+    return _simple_parse(pairs, filename)
+
+
+def simple_parse_bytes(data: bytes) -> Feed:
+    """Parse an Atom, RSS or JSON feed from a byte-string containing data."""
+    pairs = (
+        (rss.parse_rss_bytes, _adapt_rss_channel),
+        (atom.parse_atom_bytes, _adapt_atom_feed),
+        (json_feed.parse_json_feed_bytes, _adapt_json_feed)
+    )
+    return _simple_parse(pairs, data)
diff --git a/python/atoma/utils.py b/python/atoma/utils.py
new file mode 100644
index 0000000..4dc1ab5
--- /dev/null
+++ b/python/atoma/utils.py
@@ -0,0 +1,84 @@
+from datetime import datetime, timezone
+from xml.etree.ElementTree import Element
+from typing import Optional
+
+import dateutil.parser
+from defusedxml.ElementTree import parse as defused_xml_parse, ParseError
+
+from .exceptions import FeedXMLError, FeedParseError
+
+ns = {
+    'content': 'http://purl.org/rss/1.0/modules/content/',
+    'feed': 'http://www.w3.org/2005/Atom'
+}
+
+
+def parse_xml(xml_content):
+    try:
+        return defused_xml_parse(xml_content)
+    except ParseError:
+        raise FeedXMLError('Not a valid XML document')
+
+
+def get_child(element: Element, name,
+              optional: bool=True) -> Optional[Element]:
+    child = element.find(name, namespaces=ns)
+
+    if child is None and not optional:
+        raise FeedParseError(
+            'Could not parse feed: "{}" does not have a "{}"'
+            .format(element.tag, name)
+        )
+
+    elif child is None:
+        return None
+
+    return child
+
+
+def get_text(element: Element, name, optional: bool=True) -> Optional[str]:
+    child = get_child(element, name, optional)
+    if child is None:
+        return None
+
+    if child.text is None:
+        if optional:
+            return None
+
+        raise FeedParseError(
+            'Could not parse feed: "{}" text is required but is empty'
+            .format(name)
+        )
+
+    return child.text.strip()
+
+
+def get_int(element: Element, name, optional: bool=True) -> Optional[int]:
+    text = get_text(element, name, optional)
+    if text is None:
+        return None
+
+    return int(text)
+
+
+def get_datetime(element: Element, name,
+                 optional: bool=True) -> Optional[datetime]:
+    text = get_text(element, name, optional)
+    if text is None:
+        return None
+
+    return try_parse_date(text)
+
+
+def try_parse_date(date_str: str) -> Optional[datetime]:
+    try:
+        date = dateutil.parser.parse(date_str, fuzzy=True)
+    except (ValueError, OverflowError):
+        return None
+
+    if date.tzinfo is None:
+        # TZ naive datetime, make it a TZ aware datetime by assuming it
+        # contains UTC time
+        date = date.replace(tzinfo=timezone.utc)
+
+    return date
diff --git a/python/attr/__init__.py b/python/attr/__init__.py
new file mode 100644
index 0000000..debfd57
--- /dev/null
+++ b/python/attr/__init__.py
@@ -0,0 +1,65 @@
+from __future__ import absolute_import, division, print_function
+
+from functools import partial
+
+from . import converters, exceptions, filters, validators
+from ._config import get_run_validators, set_run_validators
+from ._funcs import asdict, assoc, astuple, evolve, has
+from ._make import (
+    NOTHING,
+    Attribute,
+    Factory,
+    attrib,
+    attrs,
+    fields,
+    fields_dict,
+    make_class,
+    validate,
+)
+
+
+__version__ = "18.2.0"
+
+__title__ = "attrs"
+__description__ = "Classes Without Boilerplate"
+__url__ = "https://www.attrs.org/"
+__uri__ = __url__
+__doc__ = __description__ + " <" + __uri__ + ">"
+
+__author__ = "Hynek Schlawack"
+__email__ = "hs@ox.cx"
+
+__license__ = "MIT"
+__copyright__ = "Copyright (c) 2015 Hynek Schlawack"
+
+
+s = attributes = attrs
+ib = attr = attrib
+dataclass = partial(attrs, auto_attribs=True)  # happy Easter ;)
+
+__all__ = [
+    "Attribute",
+    "Factory",
+    "NOTHING",
+    "asdict",
+    "assoc",
+    "astuple",
+    "attr",
+    "attrib",
+    "attributes",
+    "attrs",
+    "converters",
+    "evolve",
+    "exceptions",
+    "fields",
+    "fields_dict",
+    "filters",
+    "get_run_validators",
+    "has",
+    "ib",
+    "make_class",
+    "s",
+    "set_run_validators",
+    "validate",
+    "validators",
+]
diff --git a/python/attr/__init__.pyi b/python/attr/__init__.pyi
new file mode 100644
index 0000000..492fb85
--- /dev/null
+++ b/python/attr/__init__.pyi
@@ -0,0 +1,252 @@
+from typing import (
+    Any,
+    Callable,
+    Dict,
+    Generic,
+    List,
+    Optional,
+    Sequence,
+    Mapping,
+    Tuple,
+    Type,
+    TypeVar,
+    Union,
+    overload,
+)
+
+# `import X as X` is required to make these public
+from . import exceptions as exceptions
+from . import filters as filters
+from . import converters as converters
+from . import validators as validators
+
+_T = TypeVar("_T")
+_C = TypeVar("_C", bound=type)
+
+_ValidatorType = Callable[[Any, Attribute, _T], Any]
+_ConverterType = Callable[[Any], _T]
+_FilterType = Callable[[Attribute, Any], bool]
+# FIXME: in reality, if multiple validators are passed they must be in a list or tuple,
+# but those are invariant and so would prevent subtypes of _ValidatorType from working
+# when passed in a list or tuple.
+_ValidatorArgType = Union[_ValidatorType[_T], Sequence[_ValidatorType[_T]]]
+
+# _make --
+
+NOTHING: object
+
+# NOTE: Factory lies about its return type to make this possible: `x: List[int] = Factory(list)`
+# Work around mypy issue #4554 in the common case by using an overload.
+@overload
+def Factory(factory: Callable[[], _T]) -> _T: ...
+@overload
+def Factory(
+    factory: Union[Callable[[Any], _T], Callable[[], _T]],
+    takes_self: bool = ...,
+) -> _T: ...
+
+class Attribute(Generic[_T]):
+    name: str
+    default: Optional[_T]
+    validator: Optional[_ValidatorType[_T]]
+    repr: bool
+    cmp: bool
+    hash: Optional[bool]
+    init: bool
+    converter: Optional[_ConverterType[_T]]
+    metadata: Dict[Any, Any]
+    type: Optional[Type[_T]]
+    kw_only: bool
+    def __lt__(self, x: Attribute) -> bool: ...
+    def __le__(self, x: Attribute) -> bool: ...
+    def __gt__(self, x: Attribute) -> bool: ...
+    def __ge__(self, x: Attribute) -> bool: ...
+
+# NOTE: We had several choices for the annotation to use for type arg:
+# 1) Type[_T]
+#   - Pros: Handles simple cases correctly
+#   - Cons: Might produce less informative errors in the case of conflicting TypeVars
+#   e.g. `attr.ib(default='bad', type=int)`
+# 2) Callable[..., _T]
+#   - Pros: Better error messages than #1 for conflicting TypeVars
+#   - Cons: Terrible error messages for validator checks.
+#   e.g. attr.ib(type=int, validator=validate_str)
+#        -> error: Cannot infer function type argument
+# 3) type (and do all of the work in the mypy plugin)
+#   - Pros: Simple here, and we could customize the plugin with our own errors.
+#   - Cons: Would need to write mypy plugin code to handle all the cases.
+# We chose option #1.
+
+# `attr` lies about its return type to make the following possible:
+#     attr()    -> Any
+#     attr(8)   -> int
+#     attr(validator=<some callable>)  -> Whatever the callable expects.
+# This makes this type of assignments possible:
+#     x: int = attr(8)
+#
+# This form catches explicit None or no default but with no other arguments returns Any.
+@overload
+def attrib(
+    default: None = ...,
+    validator: None = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: None = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: None = ...,
+    converter: None = ...,
+    factory: None = ...,
+    kw_only: bool = ...,
+) -> Any: ...
+
+# This form catches an explicit None or no default and infers the type from the other arguments.
+@overload
+def attrib(
+    default: None = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> _T: ...
+
+# This form catches an explicit default argument.
+@overload
+def attrib(
+    default: _T,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: Optional[Type[_T]] = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> _T: ...
+
+# This form covers type=non-Type: e.g. forward references (str), Any
+@overload
+def attrib(
+    default: Optional[_T] = ...,
+    validator: Optional[_ValidatorArgType[_T]] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    convert: Optional[_ConverterType[_T]] = ...,
+    metadata: Optional[Mapping[Any, Any]] = ...,
+    type: object = ...,
+    converter: Optional[_ConverterType[_T]] = ...,
+    factory: Optional[Callable[[], _T]] = ...,
+    kw_only: bool = ...,
+) -> Any: ...
+@overload
+def attrs(
+    maybe_cls: _C,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> _C: ...
+@overload
+def attrs(
+    maybe_cls: None = ...,
+    these: Optional[Dict[str, Any]] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> Callable[[_C], _C]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+class _Fields(Tuple[Attribute, ...]):
+    def __getattr__(self, name: str) -> Attribute: ...
+
+def fields(cls: type) -> _Fields: ...
+def fields_dict(cls: type) -> Dict[str, Attribute]: ...
+def validate(inst: Any) -> None: ...
+
+# TODO: add support for returning a proper attrs class from the mypy plugin
+# we use Any instead of _CountingAttr so that e.g. `make_class('Foo', [attr.ib()])` is valid
+def make_class(
+    name: str,
+    attrs: Union[List[str], Tuple[str, ...], Dict[str, Any]],
+    bases: Tuple[type, ...] = ...,
+    repr_ns: Optional[str] = ...,
+    repr: bool = ...,
+    cmp: bool = ...,
+    hash: Optional[bool] = ...,
+    init: bool = ...,
+    slots: bool = ...,
+    frozen: bool = ...,
+    weakref_slot: bool = ...,
+    str: bool = ...,
+    auto_attribs: bool = ...,
+    kw_only: bool = ...,
+    cache_hash: bool = ...,
+) -> type: ...
+
+# _funcs --
+
+# TODO: add support for returning TypedDict from the mypy plugin
+# FIXME: asdict/astuple do not honor their factory args.  waiting on one of these:
+# https://github.com/python/mypy/issues/4236
+# https://github.com/python/typing/issues/253
+def asdict(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType] = ...,
+    dict_factory: Type[Mapping[Any, Any]] = ...,
+    retain_collection_types: bool = ...,
+) -> Dict[str, Any]: ...
+
+# TODO: add support for returning NamedTuple from the mypy plugin
+def astuple(
+    inst: Any,
+    recurse: bool = ...,
+    filter: Optional[_FilterType] = ...,
+    tuple_factory: Type[Sequence] = ...,
+    retain_collection_types: bool = ...,
+) -> Tuple[Any, ...]: ...
+def has(cls: type) -> bool: ...
+def assoc(inst: _T, **changes: Any) -> _T: ...
+def evolve(inst: _T, **changes: Any) -> _T: ...
+
+# _config --
+
+def set_run_validators(run: bool) -> None: ...
+def get_run_validators() -> bool: ...
+
+# aliases --
+
+s = attributes = attrs
+ib = attr = attrib
+dataclass = attrs  # Technically, partial(attrs, auto_attribs=True) ;)
diff --git a/python/attr/_compat.py b/python/attr/_compat.py
new file mode 100644
index 0000000..5bb0659
--- /dev/null
+++ b/python/attr/_compat.py
@@ -0,0 +1,163 @@
+from __future__ import absolute_import, division, print_function
+
+import platform
+import sys
+import types
+import warnings
+
+
+PY2 = sys.version_info[0] == 2
+PYPY = platform.python_implementation() == "PyPy"
+
+
+if PYPY or sys.version_info[:2] >= (3, 6):
+    ordered_dict = dict
+else:
+    from collections import OrderedDict
+
+    ordered_dict = OrderedDict
+
+
+if PY2:
+    from UserDict import IterableUserDict
+
+    # We 'bundle' isclass instead of using inspect as importing inspect is
+    # fairly expensive (order of 10-15 ms for a modern machine in 2016)
+    def isclass(klass):
+        return isinstance(klass, (type, types.ClassType))
+
+    # TYPE is used in exceptions, repr(int) is different on Python 2 and 3.
+    TYPE = "type"
+
+    def iteritems(d):
+        return d.iteritems()
+
+    # Python 2 is bereft of a read-only dict proxy, so we make one!
+    class ReadOnlyDict(IterableUserDict):
+        """
+        Best-effort read-only dict wrapper.
+        """
+
+        def __setitem__(self, key, val):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise TypeError(
+                "'mappingproxy' object does not support item assignment"
+            )
+
+        def update(self, _):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise AttributeError(
+                "'mappingproxy' object has no attribute 'update'"
+            )
+
+        def __delitem__(self, _):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise TypeError(
+                "'mappingproxy' object does not support item deletion"
+            )
+
+        def clear(self):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise AttributeError(
+                "'mappingproxy' object has no attribute 'clear'"
+            )
+
+        def pop(self, key, default=None):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise AttributeError(
+                "'mappingproxy' object has no attribute 'pop'"
+            )
+
+        def popitem(self):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise AttributeError(
+                "'mappingproxy' object has no attribute 'popitem'"
+            )
+
+        def setdefault(self, key, default=None):
+            # We gently pretend we're a Python 3 mappingproxy.
+            raise AttributeError(
+                "'mappingproxy' object has no attribute 'setdefault'"
+            )
+
+        def __repr__(self):
+            # Override to be identical to the Python 3 version.
+            return "mappingproxy(" + repr(self.data) + ")"
+
+    def metadata_proxy(d):
+        res = ReadOnlyDict()
+        res.data.update(d)  # We blocked update, so we have to do it like this.
+        return res
+
+
+else:
+
+    def isclass(klass):
+        return isinstance(klass, type)
+
+    TYPE = "class"
+
+    def iteritems(d):
+        return d.items()
+
+    def metadata_proxy(d):
+        return types.MappingProxyType(dict(d))
+
+
+def import_ctypes():
+    """
+    Moved into a function for testability.
+    """
+    import ctypes
+
+    return ctypes
+
+
+if not PY2:
+
+    def just_warn(*args, **kw):
+        """
+        We only warn on Python 3 because we are not aware of any concrete
+        consequences of not setting the cell on Python 2.
+        """
+        warnings.warn(
+            "Missing ctypes.  Some features like bare super() or accessing "
+            "__class__ will not work with slots classes.",
+            RuntimeWarning,
+            stacklevel=2,
+        )
+
+
+else:
+
+    def just_warn(*args, **kw):  # pragma: nocover
+        """
+        We only warn on Python 3 because we are not aware of any concrete
+        consequences of not setting the cell on Python 2.
+        """
+
+
+def make_set_closure_cell():
+    """
+    Moved into a function for testability.
+    """
+    if PYPY:  # pragma: no cover
+
+        def set_closure_cell(cell, value):
+            cell.__setstate__((value,))
+
+    else:
+        try:
+            ctypes = import_ctypes()
+
+            set_closure_cell = ctypes.pythonapi.PyCell_Set
+            set_closure_cell.argtypes = (ctypes.py_object, ctypes.py_object)
+            set_closure_cell.restype = ctypes.c_int
+        except Exception:
+            # We try best effort to set the cell, but sometimes it's not
+            # possible.  For example on Jython or on GAE.
+            set_closure_cell = just_warn
+    return set_closure_cell
+
+
+set_closure_cell = make_set_closure_cell()
diff --git a/python/attr/_config.py b/python/attr/_config.py
new file mode 100644
index 0000000..8ec9209
--- /dev/null
+++ b/python/attr/_config.py
@@ -0,0 +1,23 @@
+from __future__ import absolute_import, division, print_function
+
+
+__all__ = ["set_run_validators", "get_run_validators"]
+
+_run_validators = True
+
+
+def set_run_validators(run):
+    """
+    Set whether or not validators are run.  By default, they are run.
+    """
+    if not isinstance(run, bool):
+        raise TypeError("'run' must be bool.")
+    global _run_validators
+    _run_validators = run
+
+
+def get_run_validators():
+    """
+    Return whether or not validators are run.
+    """
+    return _run_validators
diff --git a/python/attr/_funcs.py b/python/attr/_funcs.py
new file mode 100644
index 0000000..b61d239
--- /dev/null
+++ b/python/attr/_funcs.py
@@ -0,0 +1,290 @@
+from __future__ import absolute_import, division, print_function
+
+import copy
+
+from ._compat import iteritems
+from ._make import NOTHING, _obj_setattr, fields
+from .exceptions import AttrsAttributeNotFoundError
+
+
+def asdict(
+    inst,
+    recurse=True,
+    filter=None,
+    dict_factory=dict,
+    retain_collection_types=False,
+):
+    """
+    Return the ``attrs`` attribute values of *inst* as a dict.
+
+    Optionally recurse into other ``attrs``-decorated classes.
+
+    :param inst: Instance of an ``attrs``-decorated class.
+    :param bool recurse: Recurse into classes that are also
+        ``attrs``-decorated.
+    :param callable filter: A callable whose return code determines whether an
+        attribute or element is included (``True``) or dropped (``False``).  Is
+        called with the :class:`attr.Attribute` as the first argument and the
+        value as the second argument.
+    :param callable dict_factory: A callable to produce dictionaries from.  For
+        example, to produce ordered dictionaries instead of normal Python
+        dictionaries, pass in ``collections.OrderedDict``.
+    :param bool retain_collection_types: Do not convert to ``list`` when
+        encountering an attribute whose type is ``tuple`` or ``set``.  Only
+        meaningful if ``recurse`` is ``True``.
+
+    :rtype: return type of *dict_factory*
+
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 16.0.0 *dict_factory*
+    ..  versionadded:: 16.1.0 *retain_collection_types*
+    """
+    attrs = fields(inst.__class__)
+    rv = dict_factory()
+    for a in attrs:
+        v = getattr(inst, a.name)
+        if filter is not None and not filter(a, v):
+            continue
+        if recurse is True:
+            if has(v.__class__):
+                rv[a.name] = asdict(
+                    v, True, filter, dict_factory, retain_collection_types
+                )
+            elif isinstance(v, (tuple, list, set)):
+                cf = v.__class__ if retain_collection_types is True else list
+                rv[a.name] = cf(
+                    [
+                        _asdict_anything(
+                            i, filter, dict_factory, retain_collection_types
+                        )
+                        for i in v
+                    ]
+                )
+            elif isinstance(v, dict):
+                df = dict_factory
+                rv[a.name] = df(
+                    (
+                        _asdict_anything(
+                            kk, filter, df, retain_collection_types
+                        ),
+                        _asdict_anything(
+                            vv, filter, df, retain_collection_types
+                        ),
+                    )
+                    for kk, vv in iteritems(v)
+                )
+            else:
+                rv[a.name] = v
+        else:
+            rv[a.name] = v
+    return rv
+
+
+def _asdict_anything(val, filter, dict_factory, retain_collection_types):
+    """
+    ``asdict`` only works on attrs instances, this works on anything.
+    """
+    if getattr(val.__class__, "__attrs_attrs__", None) is not None:
+        # Attrs class.
+        rv = asdict(val, True, filter, dict_factory, retain_collection_types)
+    elif isinstance(val, (tuple, list, set)):
+        cf = val.__class__ if retain_collection_types is True else list
+        rv = cf(
+            [
+                _asdict_anything(
+                    i, filter, dict_factory, retain_collection_types
+                )
+                for i in val
+            ]
+        )
+    elif isinstance(val, dict):
+        df = dict_factory
+        rv = df(
+            (
+                _asdict_anything(kk, filter, df, retain_collection_types),
+                _asdict_anything(vv, filter, df, retain_collection_types),
+            )
+            for kk, vv in iteritems(val)
+        )
+    else:
+        rv = val
+    return rv
+
+
+def astuple(
+    inst,
+    recurse=True,
+    filter=None,
+    tuple_factory=tuple,
+    retain_collection_types=False,
+):
+    """
+    Return the ``attrs`` attribute values of *inst* as a tuple.
+
+    Optionally recurse into other ``attrs``-decorated classes.
+
+    :param inst: Instance of an ``attrs``-decorated class.
+    :param bool recurse: Recurse into classes that are also
+        ``attrs``-decorated.
+    :param callable filter: A callable whose return code determines whether an
+        attribute or element is included (``True``) or dropped (``False``).  Is
+        called with the :class:`attr.Attribute` as the first argument and the
+        value as the second argument.
+    :param callable tuple_factory: A callable to produce tuples from.  For
+        example, to produce lists instead of tuples.
+    :param bool retain_collection_types: Do not convert to ``list``
+        or ``dict`` when encountering an attribute which type is
+        ``tuple``, ``dict`` or ``set``.  Only meaningful if ``recurse`` is
+        ``True``.
+
+    :rtype: return type of *tuple_factory*
+
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 16.2.0
+    """
+    attrs = fields(inst.__class__)
+    rv = []
+    retain = retain_collection_types  # Very long. :/
+    for a in attrs:
+        v = getattr(inst, a.name)
+        if filter is not None and not filter(a, v):
+            continue
+        if recurse is True:
+            if has(v.__class__):
+                rv.append(
+                    astuple(
+                        v,
+                        recurse=True,
+                        filter=filter,
+                        tuple_factory=tuple_factory,
+                        retain_collection_types=retain,
+                    )
+                )
+            elif isinstance(v, (tuple, list, set)):
+                cf = v.__class__ if retain is True else list
+                rv.append(
+                    cf(
+                        [
+                            astuple(
+                                j,
+                                recurse=True,
+                                filter=filter,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(j.__class__)
+                            else j
+                            for j in v
+                        ]
+                    )
+                )
+            elif isinstance(v, dict):
+                df = v.__class__ if retain is True else dict
+                rv.append(
+                    df(
+                        (
+                            astuple(
+                                kk,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(kk.__class__)
+                            else kk,
+                            astuple(
+                                vv,
+                                tuple_factory=tuple_factory,
+                                retain_collection_types=retain,
+                            )
+                            if has(vv.__class__)
+                            else vv,
+                        )
+                        for kk, vv in iteritems(v)
+                    )
+                )
+            else:
+                rv.append(v)
+        else:
+            rv.append(v)
+    return rv if tuple_factory is list else tuple_factory(rv)
+
+
+def has(cls):
+    """
+    Check whether *cls* is a class with ``attrs`` attributes.
+
+    :param type cls: Class to introspect.
+    :raise TypeError: If *cls* is not a class.
+
+    :rtype: :class:`bool`
+    """
+    return getattr(cls, "__attrs_attrs__", None) is not None
+
+
+def assoc(inst, **changes):
+    """
+    Copy *inst* and apply *changes*.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    :param changes: Keyword changes in the new copy.
+
+    :return: A copy of inst with *changes* incorporated.
+
+    :raise attr.exceptions.AttrsAttributeNotFoundError: If *attr_name* couldn't
+        be found on *cls*.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  deprecated:: 17.1.0
+        Use :func:`evolve` instead.
+    """
+    import warnings
+
+    warnings.warn(
+        "assoc is deprecated and will be removed after 2018/01.",
+        DeprecationWarning,
+        stacklevel=2,
+    )
+    new = copy.copy(inst)
+    attrs = fields(inst.__class__)
+    for k, v in iteritems(changes):
+        a = getattr(attrs, k, NOTHING)
+        if a is NOTHING:
+            raise AttrsAttributeNotFoundError(
+                "{k} is not an attrs attribute on {cl}.".format(
+                    k=k, cl=new.__class__
+                )
+            )
+        _obj_setattr(new, k, v)
+    return new
+
+
+def evolve(inst, **changes):
+    """
+    Create a new instance, based on *inst* with *changes* applied.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    :param changes: Keyword changes in the new copy.
+
+    :return: A copy of inst with *changes* incorporated.
+
+    :raise TypeError: If *attr_name* couldn't be found in the class
+        ``__init__``.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    ..  versionadded:: 17.1.0
+    """
+    cls = inst.__class__
+    attrs = fields(cls)
+    for a in attrs:
+        if not a.init:
+            continue
+        attr_name = a.name  # To deal with private attributes.
+        init_name = attr_name if attr_name[0] != "_" else attr_name[1:]
+        if init_name not in changes:
+            changes[init_name] = getattr(inst, attr_name)
+    return cls(**changes)
diff --git a/python/attr/_make.py b/python/attr/_make.py
new file mode 100644
index 0000000..f7fd05e
--- /dev/null
+++ b/python/attr/_make.py
@@ -0,0 +1,2034 @@
+from __future__ import absolute_import, division, print_function
+
+import copy
+import hashlib
+import linecache
+import sys
+import threading
+import warnings
+
+from operator import itemgetter
+
+from . import _config
+from ._compat import (
+    PY2,
+    isclass,
+    iteritems,
+    metadata_proxy,
+    ordered_dict,
+    set_closure_cell,
+)
+from .exceptions import (
+    DefaultAlreadySetError,
+    FrozenInstanceError,
+    NotAnAttrsClassError,
+    PythonTooOldError,
+    UnannotatedAttributeError,
+)
+
+
+# This is used at least twice, so cache it here.
+_obj_setattr = object.__setattr__
+_init_converter_pat = "__attr_converter_{}"
+_init_factory_pat = "__attr_factory_{}"
+_tuple_property_pat = (
+    "    {attr_name} = _attrs_property(_attrs_itemgetter({index}))"
+)
+_classvar_prefixes = ("typing.ClassVar", "t.ClassVar", "ClassVar")
+# we don't use a double-underscore prefix because that triggers
+# name mangling when trying to create a slot for the field
+# (when slots=True)
+_hash_cache_field = "_attrs_cached_hash"
+
+_empty_metadata_singleton = metadata_proxy({})
+
+
+class _Nothing(object):
+    """
+    Sentinel class to indicate the lack of a value when ``None`` is ambiguous.
+
+    ``_Nothing`` is a singleton. There is only ever one of it.
+    """
+
+    _singleton = None
+
+    def __new__(cls):
+        if _Nothing._singleton is None:
+            _Nothing._singleton = super(_Nothing, cls).__new__(cls)
+        return _Nothing._singleton
+
+    def __repr__(self):
+        return "NOTHING"
+
+
+NOTHING = _Nothing()
+"""
+Sentinel to indicate the lack of a value when ``None`` is ambiguous.
+"""
+
+
+def attrib(
+    default=NOTHING,
+    validator=None,
+    repr=True,
+    cmp=True,
+    hash=None,
+    init=True,
+    convert=None,
+    metadata=None,
+    type=None,
+    converter=None,
+    factory=None,
+    kw_only=False,
+):
+    """
+    Create a new attribute on a class.
+
+    ..  warning::
+
+        Does *not* do anything unless the class is also decorated with
+        :func:`attr.s`!
+
+    :param default: A value that is used if an ``attrs``-generated ``__init__``
+        is used and no value is passed while instantiating or the attribute is
+        excluded using ``init=False``.
+
+        If the value is an instance of :class:`Factory`, its callable will be
+        used to construct a new value (useful for mutable data types like lists
+        or dicts).
+
+        If a default is not set (or set manually to ``attr.NOTHING``), a value
+        *must* be supplied when instantiating; otherwise a :exc:`TypeError`
+        will be raised.
+
+        The default can also be set using decorator notation as shown below.
+
+    :type default: Any value.
+
+    :param callable factory: Syntactic sugar for
+        ``default=attr.Factory(callable)``.
+
+    :param validator: :func:`callable` that is called by ``attrs``-generated
+        ``__init__`` methods after the instance has been initialized.  They
+        receive the initialized instance, the :class:`Attribute`, and the
+        passed value.
+
+        The return value is *not* inspected so the validator has to throw an
+        exception itself.
+
+        If a ``list`` is passed, its items are treated as validators and must
+        all pass.
+
+        Validators can be globally disabled and re-enabled using
+        :func:`get_run_validators`.
+
+        The validator can also be set using decorator notation as shown below.
+
+    :type validator: ``callable`` or a ``list`` of ``callable``\\ s.
+
+    :param bool repr: Include this attribute in the generated ``__repr__``
+        method.
+    :param bool cmp: Include this attribute in the generated comparison methods
+        (``__eq__`` et al).
+    :param hash: Include this attribute in the generated ``__hash__``
+        method.  If ``None`` (default), mirror *cmp*'s value.  This is the
+        correct behavior according the Python spec.  Setting this value to
+        anything else than ``None`` is *discouraged*.
+    :type hash: ``bool`` or ``None``
+    :param bool init: Include this attribute in the generated ``__init__``
+        method.  It is possible to set this to ``False`` and set a default
+        value.  In that case this attributed is unconditionally initialized
+        with the specified default value or factory.
+    :param callable converter: :func:`callable` that is called by
+        ``attrs``-generated ``__init__`` methods to converter attribute's value
+        to the desired format.  It is given the passed-in value, and the
+        returned value will be used as the new value of the attribute.  The
+        value is converted before being passed to the validator, if any.
+    :param metadata: An arbitrary mapping, to be used by third-party
+        components.  See :ref:`extending_metadata`.
+    :param type: The type of the attribute.  In Python 3.6 or greater, the
+        preferred method to specify the type is using a variable annotation
+        (see `PEP 526 <https://www.python.org/dev/peps/pep-0526/>`_).
+        This argument is provided for backward compatibility.
+        Regardless of the approach used, the type will be stored on
+        ``Attribute.type``.
+
+        Please note that ``attrs`` doesn't do anything with this metadata by
+        itself. You can use it as part of your own code or for
+        :doc:`static type checking <types>`.
+    :param kw_only: Make this attribute keyword-only (Python 3+)
+        in the generated ``__init__`` (if ``init`` is ``False``, this
+        parameter is ignored).
+
+    .. versionadded:: 15.2.0 *convert*
+    .. versionadded:: 16.3.0 *metadata*
+    .. versionchanged:: 17.1.0 *validator* can be a ``list`` now.
+    .. versionchanged:: 17.1.0
+       *hash* is ``None`` and therefore mirrors *cmp* by default.
+    .. versionadded:: 17.3.0 *type*
+    .. deprecated:: 17.4.0 *convert*
+    .. versionadded:: 17.4.0 *converter* as a replacement for the deprecated
+       *convert* to achieve consistency with other noun-based arguments.
+    .. versionadded:: 18.1.0
+       ``factory=f`` is syntactic sugar for ``default=attr.Factory(f)``.
+    .. versionadded:: 18.2.0 *kw_only*
+    """
+    if hash is not None and hash is not True and hash is not False:
+        raise TypeError(
+            "Invalid value for hash.  Must be True, False, or None."
+        )
+
+    if convert is not None:
+        if converter is not None:
+            raise RuntimeError(
+                "Can't pass both `convert` and `converter`.  "
+                "Please use `converter` only."
+            )
+        warnings.warn(
+            "The `convert` argument is deprecated in favor of `converter`.  "
+            "It will be removed after 2019/01.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        converter = convert
+
+    if factory is not None:
+        if default is not NOTHING:
+            raise ValueError(
+                "The `default` and `factory` arguments are mutually "
+                "exclusive."
+            )
+        if not callable(factory):
+            raise ValueError("The `factory` argument must be a callable.")
+        default = Factory(factory)
+
+    if metadata is None:
+        metadata = {}
+
+    return _CountingAttr(
+        default=default,
+        validator=validator,
+        repr=repr,
+        cmp=cmp,
+        hash=hash,
+        init=init,
+        converter=converter,
+        metadata=metadata,
+        type=type,
+        kw_only=kw_only,
+    )
+
+
+def _make_attr_tuple_class(cls_name, attr_names):
+    """
+    Create a tuple subclass to hold `Attribute`s for an `attrs` class.
+
+    The subclass is a bare tuple with properties for names.
+
+    class MyClassAttributes(tuple):
+        __slots__ = ()
+        x = property(itemgetter(0))
+    """
+    attr_class_name = "{}Attributes".format(cls_name)
+    attr_class_template = [
+        "class {}(tuple):".format(attr_class_name),
+        "    __slots__ = ()",
+    ]
+    if attr_names:
+        for i, attr_name in enumerate(attr_names):
+            attr_class_template.append(
+                _tuple_property_pat.format(index=i, attr_name=attr_name)
+            )
+    else:
+        attr_class_template.append("    pass")
+    globs = {"_attrs_itemgetter": itemgetter, "_attrs_property": property}
+    eval(compile("\n".join(attr_class_template), "", "exec"), globs)
+
+    return globs[attr_class_name]
+
+
+# Tuple class for extracted attributes from a class definition.
+# `base_attrs` is a subset of `attrs`.
+_Attributes = _make_attr_tuple_class(
+    "_Attributes",
+    [
+        # all attributes to build dunder methods for
+        "attrs",
+        # attributes that have been inherited
+        "base_attrs",
+        # map inherited attributes to their originating classes
+        "base_attrs_map",
+    ],
+)
+
+
+def _is_class_var(annot):
+    """
+    Check whether *annot* is a typing.ClassVar.
+
+    The string comparison hack is used to avoid evaluating all string
+    annotations which would put attrs-based classes at a performance
+    disadvantage compared to plain old classes.
+    """
+    return str(annot).startswith(_classvar_prefixes)
+
+
+def _get_annotations(cls):
+    """
+    Get annotations for *cls*.
+    """
+    anns = getattr(cls, "__annotations__", None)
+    if anns is None:
+        return {}
+
+    # Verify that the annotations aren't merely inherited.
+    for base_cls in cls.__mro__[1:]:
+        if anns is getattr(base_cls, "__annotations__", None):
+            return {}
+
+    return anns
+
+
+def _counter_getter(e):
+    """
+    Key function for sorting to avoid re-creating a lambda for every class.
+    """
+    return e[1].counter
+
+
+def _transform_attrs(cls, these, auto_attribs, kw_only):
+    """
+    Transform all `_CountingAttr`s on a class into `Attribute`s.
+
+    If *these* is passed, use that and don't look for them on the class.
+
+    Return an `_Attributes`.
+    """
+    cd = cls.__dict__
+    anns = _get_annotations(cls)
+
+    if these is not None:
+        ca_list = [(name, ca) for name, ca in iteritems(these)]
+
+        if not isinstance(these, ordered_dict):
+            ca_list.sort(key=_counter_getter)
+    elif auto_attribs is True:
+        ca_names = {
+            name
+            for name, attr in cd.items()
+            if isinstance(attr, _CountingAttr)
+        }
+        ca_list = []
+        annot_names = set()
+        for attr_name, type in anns.items():
+            if _is_class_var(type):
+                continue
+            annot_names.add(attr_name)
+            a = cd.get(attr_name, NOTHING)
+            if not isinstance(a, _CountingAttr):
+                if a is NOTHING:
+                    a = attrib()
+                else:
+                    a = attrib(default=a)
+            ca_list.append((attr_name, a))
+
+        unannotated = ca_names - annot_names
+        if len(unannotated) > 0:
+            raise UnannotatedAttributeError(
+                "The following `attr.ib`s lack a type annotation: "
+                + ", ".join(
+                    sorted(unannotated, key=lambda n: cd.get(n).counter)
+                )
+                + "."
+            )
+    else:
+        ca_list = sorted(
+            (
+                (name, attr)
+                for name, attr in cd.items()
+                if isinstance(attr, _CountingAttr)
+            ),
+            key=lambda e: e[1].counter,
+        )
+
+    own_attrs = [
+        Attribute.from_counting_attr(
+            name=attr_name, ca=ca, type=anns.get(attr_name)
+        )
+        for attr_name, ca in ca_list
+    ]
+
+    base_attrs = []
+    base_attr_map = {}  # A dictionary of base attrs to their classes.
+    taken_attr_names = {a.name: a for a in own_attrs}
+
+    # Traverse the MRO and collect attributes.
+    for base_cls in cls.__mro__[1:-1]:
+        sub_attrs = getattr(base_cls, "__attrs_attrs__", None)
+        if sub_attrs is not None:
+            for a in sub_attrs:
+                prev_a = taken_attr_names.get(a.name)
+                # Only add an attribute if it hasn't been defined before.  This
+                # allows for overwriting attribute definitions by subclassing.
+                if prev_a is None:
+                    base_attrs.append(a)
+                    taken_attr_names[a.name] = a
+                    base_attr_map[a.name] = base_cls
+
+    attr_names = [a.name for a in base_attrs + own_attrs]
+
+    AttrsClass = _make_attr_tuple_class(cls.__name__, attr_names)
+
+    if kw_only:
+        own_attrs = [a._assoc(kw_only=True) for a in own_attrs]
+        base_attrs = [a._assoc(kw_only=True) for a in base_attrs]
+
+    attrs = AttrsClass(base_attrs + own_attrs)
+
+    had_default = False
+    was_kw_only = False
+    for a in attrs:
+        if (
+            was_kw_only is False
+            and had_default is True
+            and a.default is NOTHING
+            and a.init is True
+            and a.kw_only is False
+        ):
+            raise ValueError(
+                "No mandatory attributes allowed after an attribute with a "
+                "default value or factory.  Attribute in question: %r" % (a,)
+            )
+        elif (
+            had_default is False
+            and a.default is not NOTHING
+            and a.init is not False
+            and
+            # Keyword-only attributes without defaults can be specified
+            # after keyword-only attributes with defaults.
+            a.kw_only is False
+        ):
+            had_default = True
+        if was_kw_only is True and a.kw_only is False:
+            raise ValueError(
+                "Non keyword-only attributes are not allowed after a "
+                "keyword-only attribute.  Attribute in question: {a!r}".format(
+                    a=a
+                )
+            )
+        if was_kw_only is False and a.init is True and a.kw_only is True:
+            was_kw_only = True
+
+    return _Attributes((attrs, base_attrs, base_attr_map))
+
+
+def _frozen_setattrs(self, name, value):
+    """
+    Attached to frozen classes as __setattr__.
+    """
+    raise FrozenInstanceError()
+
+
+def _frozen_delattrs(self, name):
+    """
+    Attached to frozen classes as __delattr__.
+    """
+    raise FrozenInstanceError()
+
+
+class _ClassBuilder(object):
+    """
+    Iteratively build *one* class.
+    """
+
+    __slots__ = (
+        "_cls",
+        "_cls_dict",
+        "_attrs",
+        "_base_names",
+        "_attr_names",
+        "_slots",
+        "_frozen",
+        "_weakref_slot",
+        "_cache_hash",
+        "_has_post_init",
+        "_delete_attribs",
+        "_base_attr_map",
+    )
+
+    def __init__(
+        self,
+        cls,
+        these,
+        slots,
+        frozen,
+        weakref_slot,
+        auto_attribs,
+        kw_only,
+        cache_hash,
+    ):
+        attrs, base_attrs, base_map = _transform_attrs(
+            cls, these, auto_attribs, kw_only
+        )
+
+        self._cls = cls
+        self._cls_dict = dict(cls.__dict__) if slots else {}
+        self._attrs = attrs
+        self._base_names = set(a.name for a in base_attrs)
+        self._base_attr_map = base_map
+        self._attr_names = tuple(a.name for a in attrs)
+        self._slots = slots
+        self._frozen = frozen or _has_frozen_base_class(cls)
+        self._weakref_slot = weakref_slot
+        self._cache_hash = cache_hash
+        self._has_post_init = bool(getattr(cls, "__attrs_post_init__", False))
+        self._delete_attribs = not bool(these)
+
+        self._cls_dict["__attrs_attrs__"] = self._attrs
+
+        if frozen:
+            self._cls_dict["__setattr__"] = _frozen_setattrs
+            self._cls_dict["__delattr__"] = _frozen_delattrs
+
+    def __repr__(self):
+        return "<_ClassBuilder(cls={cls})>".format(cls=self._cls.__name__)
+
+    def build_class(self):
+        """
+        Finalize class based on the accumulated configuration.
+
+        Builder cannot be used after calling this method.
+        """
+        if self._slots is True:
+            return self._create_slots_class()
+        else:
+            return self._patch_original_class()
+
+    def _patch_original_class(self):
+        """
+        Apply accumulated methods and return the class.
+        """
+        cls = self._cls
+        base_names = self._base_names
+
+        # Clean class of attribute definitions (`attr.ib()`s).
+        if self._delete_attribs:
+            for name in self._attr_names:
+                if (
+                    name not in base_names
+                    and getattr(cls, name, None) is not None
+                ):
+                    try:
+                        delattr(cls, name)
+                    except AttributeError:
+                        # This can happen if a base class defines a class
+                        # variable and we want to set an attribute with the
+                        # same name by using only a type annotation.
+                        pass
+
+        # Attach our dunder methods.
+        for name, value in self._cls_dict.items():
+            setattr(cls, name, value)
+
+        return cls
+
+    def _create_slots_class(self):
+        """
+        Build and return a new class with a `__slots__` attribute.
+        """
+        base_names = self._base_names
+        cd = {
+            k: v
+            for k, v in iteritems(self._cls_dict)
+            if k not in tuple(self._attr_names) + ("__dict__", "__weakref__")
+        }
+
+        weakref_inherited = False
+
+        # Traverse the MRO to check for an existing __weakref__.
+        for base_cls in self._cls.__mro__[1:-1]:
+            if "__weakref__" in getattr(base_cls, "__dict__", ()):
+                weakref_inherited = True
+                break
+
+        names = self._attr_names
+        if (
+            self._weakref_slot
+            and "__weakref__" not in getattr(self._cls, "__slots__", ())
+            and "__weakref__" not in names
+            and not weakref_inherited
+        ):
+            names += ("__weakref__",)
+
+        # We only add the names of attributes that aren't inherited.
+        # Settings __slots__ to inherited attributes wastes memory.
+        slot_names = [name for name in names if name not in base_names]
+        if self._cache_hash:
+            slot_names.append(_hash_cache_field)
+        cd["__slots__"] = tuple(slot_names)
+
+        qualname = getattr(self._cls, "__qualname__", None)
+        if qualname is not None:
+            cd["__qualname__"] = qualname
+
+        # __weakref__ is not writable.
+        state_attr_names = tuple(
+            an for an in self._attr_names if an != "__weakref__"
+        )
+
+        def slots_getstate(self):
+            """
+            Automatically created by attrs.
+            """
+            return tuple(getattr(self, name) for name in state_attr_names)
+
+        def slots_setstate(self, state):
+            """
+            Automatically created by attrs.
+            """
+            __bound_setattr = _obj_setattr.__get__(self, Attribute)
+            for name, value in zip(state_attr_names, state):
+                __bound_setattr(name, value)
+
+        # slots and frozen require __getstate__/__setstate__ to work
+        cd["__getstate__"] = slots_getstate
+        cd["__setstate__"] = slots_setstate
+
+        # Create new class based on old class and our methods.
+        cls = type(self._cls)(self._cls.__name__, self._cls.__bases__, cd)
+
+        # The following is a fix for
+        # https://github.com/python-attrs/attrs/issues/102.  On Python 3,
+        # if a method mentions `__class__` or uses the no-arg super(), the
+        # compiler will bake a reference to the class in the method itself
+        # as `method.__closure__`.  Since we replace the class with a
+        # clone, we rewrite these references so it keeps working.
+        for item in cls.__dict__.values():
+            if isinstance(item, (classmethod, staticmethod)):
+                # Class- and staticmethods hide their functions inside.
+                # These might need to be rewritten as well.
+                closure_cells = getattr(item.__func__, "__closure__", None)
+            else:
+                closure_cells = getattr(item, "__closure__", None)
+
+            if not closure_cells:  # Catch None or the empty list.
+                continue
+            for cell in closure_cells:
+                if cell.cell_contents is self._cls:
+                    set_closure_cell(cell, cls)
+
+        return cls
+
+    def add_repr(self, ns):
+        self._cls_dict["__repr__"] = self._add_method_dunders(
+            _make_repr(self._attrs, ns=ns)
+        )
+        return self
+
+    def add_str(self):
+        repr = self._cls_dict.get("__repr__")
+        if repr is None:
+            raise ValueError(
+                "__str__ can only be generated if a __repr__ exists."
+            )
+
+        def __str__(self):
+            return self.__repr__()
+
+        self._cls_dict["__str__"] = self._add_method_dunders(__str__)
+        return self
+
+    def make_unhashable(self):
+        self._cls_dict["__hash__"] = None
+        return self
+
+    def add_hash(self):
+        self._cls_dict["__hash__"] = self._add_method_dunders(
+            _make_hash(
+                self._attrs, frozen=self._frozen, cache_hash=self._cache_hash
+            )
+        )
+
+        return self
+
+    def add_init(self):
+        self._cls_dict["__init__"] = self._add_method_dunders(
+            _make_init(
+                self._attrs,
+                self._has_post_init,
+                self._frozen,
+                self._slots,
+                self._cache_hash,
+                self._base_attr_map,
+            )
+        )
+
+        return self
+
+    def add_cmp(self):
+        cd = self._cls_dict
+
+        cd["__eq__"], cd["__ne__"], cd["__lt__"], cd["__le__"], cd[
+            "__gt__"
+        ], cd["__ge__"] = (
+            self._add_method_dunders(meth) for meth in _make_cmp(self._attrs)
+        )
+
+        return self
+
+    def _add_method_dunders(self, method):
+        """
+        Add __module__ and __qualname__ to a *method* if possible.
+        """
+        try:
+            method.__module__ = self._cls.__module__
+        except AttributeError:
+            pass
+
+        try:
+            method.__qualname__ = ".".join(
+                (self._cls.__qualname__, method.__name__)
+            )
+        except AttributeError:
+            pass
+
+        return method
+
+
+def attrs(
+    maybe_cls=None,
+    these=None,
+    repr_ns=None,
+    repr=True,
+    cmp=True,
+    hash=None,
+    init=True,
+    slots=False,
+    frozen=False,
+    weakref_slot=True,
+    str=False,
+    auto_attribs=False,
+    kw_only=False,
+    cache_hash=False,
+):
+    r"""
+    A class decorator that adds `dunder
+    <https://wiki.python.org/moin/DunderAlias>`_\ -methods according to the
+    specified attributes using :func:`attr.ib` or the *these* argument.
+
+    :param these: A dictionary of name to :func:`attr.ib` mappings.  This is
+        useful to avoid the definition of your attributes within the class body
+        because you can't (e.g. if you want to add ``__repr__`` methods to
+        Django models) or don't want to.
+
+        If *these* is not ``None``, ``attrs`` will *not* search the class body
+        for attributes and will *not* remove any attributes from it.
+
+        If *these* is an ordered dict (:class:`dict` on Python 3.6+,
+        :class:`collections.OrderedDict` otherwise), the order is deduced from
+        the order of the attributes inside *these*.  Otherwise the order
+        of the definition of the attributes is used.
+
+    :type these: :class:`dict` of :class:`str` to :func:`attr.ib`
+
+    :param str repr_ns: When using nested classes, there's no way in Python 2
+        to automatically detect that.  Therefore it's possible to set the
+        namespace explicitly for a more meaningful ``repr`` output.
+    :param bool repr: Create a ``__repr__`` method with a human readable
+        representation of ``attrs`` attributes..
+    :param bool str: Create a ``__str__`` method that is identical to
+        ``__repr__``.  This is usually not necessary except for
+        :class:`Exception`\ s.
+    :param bool cmp: Create ``__eq__``, ``__ne__``, ``__lt__``, ``__le__``,
+        ``__gt__``, and ``__ge__`` methods that compare the class as if it were
+        a tuple of its ``attrs`` attributes.  But the attributes are *only*
+        compared, if the types of both classes are *identical*!
+    :param hash: If ``None`` (default), the ``__hash__`` method is generated
+        according how *cmp* and *frozen* are set.
+
+        1. If *both* are True, ``attrs`` will generate a ``__hash__`` for you.
+        2. If *cmp* is True and *frozen* is False, ``__hash__`` will be set to
+           None, marking it unhashable (which it is).
+        3. If *cmp* is False, ``__hash__`` will be left untouched meaning the
+           ``__hash__`` method of the base class will be used (if base class is
+           ``object``, this means it will fall back to id-based hashing.).
+
+        Although not recommended, you can decide for yourself and force
+        ``attrs`` to create one (e.g. if the class is immutable even though you
+        didn't freeze it programmatically) by passing ``True`` or not.  Both of
+        these cases are rather special and should be used carefully.
+
+        See the `Python documentation \
+        <https://docs.python.org/3/reference/datamodel.html#object.__hash__>`_
+        and the `GitHub issue that led to the default behavior \
+        <https://github.com/python-attrs/attrs/issues/136>`_ for more details.
+    :type hash: ``bool`` or ``None``
+    :param bool init: Create a ``__init__`` method that initializes the
+        ``attrs`` attributes.  Leading underscores are stripped for the
+        argument name.  If a ``__attrs_post_init__`` method exists on the
+        class, it will be called after the class is fully initialized.
+    :param bool slots: Create a slots_-style class that's more
+        memory-efficient.  See :ref:`slots` for further ramifications.
+    :param bool frozen: Make instances immutable after initialization.  If
+        someone attempts to modify a frozen instance,
+        :exc:`attr.exceptions.FrozenInstanceError` is raised.
+
+        Please note:
+
+            1. This is achieved by installing a custom ``__setattr__`` method
+               on your class so you can't implement an own one.
+
+            2. True immutability is impossible in Python.
+
+            3. This *does* have a minor a runtime performance :ref:`impact
+               <how-frozen>` when initializing new instances.  In other words:
+               ``__init__`` is slightly slower with ``frozen=True``.
+
+            4. If a class is frozen, you cannot modify ``self`` in
+               ``__attrs_post_init__`` or a self-written ``__init__``. You can
+               circumvent that limitation by using
+               ``object.__setattr__(self, "attribute_name", value)``.
+
+        ..  _slots: https://docs.python.org/3/reference/datamodel.html#slots
+    :param bool weakref_slot: Make instances weak-referenceable.  This has no
+        effect unless ``slots`` is also enabled.
+    :param bool auto_attribs: If True, collect `PEP 526`_-annotated attributes
+        (Python 3.6 and later only) from the class body.
+
+        In this case, you **must** annotate every field.  If ``attrs``
+        encounters a field that is set to an :func:`attr.ib` but lacks a type
+        annotation, an :exc:`attr.exceptions.UnannotatedAttributeError` is
+        raised.  Use ``field_name: typing.Any = attr.ib(...)`` if you don't
+        want to set a type.
+
+        If you assign a value to those attributes (e.g. ``x: int = 42``), that
+        value becomes the default value like if it were passed using
+        ``attr.ib(default=42)``.  Passing an instance of :class:`Factory` also
+        works as expected.
+
+        Attributes annotated as :data:`typing.ClassVar` are **ignored**.
+
+        .. _`PEP 526`: https://www.python.org/dev/peps/pep-0526/
+    :param bool kw_only: Make all attributes keyword-only (Python 3+)
+        in the generated ``__init__`` (if ``init`` is ``False``, this
+        parameter is ignored).
+    :param bool cache_hash: Ensure that the object's hash code is computed
+        only once and stored on the object.  If this is set to ``True``,
+        hashing must be either explicitly or implicitly enabled for this
+        class.  If the hash code is cached, then no attributes of this
+        class which participate in hash code computation may be mutated
+        after object creation.
+
+
+    .. versionadded:: 16.0.0 *slots*
+    .. versionadded:: 16.1.0 *frozen*
+    .. versionadded:: 16.3.0 *str*
+    .. versionadded:: 16.3.0 Support for ``__attrs_post_init__``.
+    .. versionchanged:: 17.1.0
+       *hash* supports ``None`` as value which is also the default now.
+    .. versionadded:: 17.3.0 *auto_attribs*
+    .. versionchanged:: 18.1.0
+       If *these* is passed, no attributes are deleted from the class body.
+    .. versionchanged:: 18.1.0 If *these* is ordered, the order is retained.
+    .. versionadded:: 18.2.0 *weakref_slot*
+    .. deprecated:: 18.2.0
+       ``__lt__``, ``__le__``, ``__gt__``, and ``__ge__`` now raise a
+       :class:`DeprecationWarning` if the classes compared are subclasses of
+       each other. ``__eq`` and ``__ne__`` never tried to compared subclasses
+       to each other.
+    .. versionadded:: 18.2.0 *kw_only*
+    .. versionadded:: 18.2.0 *cache_hash*
+    """
+
+    def wrap(cls):
+        if getattr(cls, "__class__", None) is None:
+            raise TypeError("attrs only works with new-style classes.")
+
+        builder = _ClassBuilder(
+            cls,
+            these,
+            slots,
+            frozen,
+            weakref_slot,
+            auto_attribs,
+            kw_only,
+            cache_hash,
+        )
+
+        if repr is True:
+            builder.add_repr(repr_ns)
+        if str is True:
+            builder.add_str()
+        if cmp is True:
+            builder.add_cmp()
+
+        if hash is not True and hash is not False and hash is not None:
+            # Can't use `hash in` because 1 == True for example.
+            raise TypeError(
+                "Invalid value for hash.  Must be True, False, or None."
+            )
+        elif hash is False or (hash is None and cmp is False):
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " hashing must be either explicitly or implicitly "
+                    "enabled."
+                )
+        elif hash is True or (hash is None and cmp is True and frozen is True):
+            builder.add_hash()
+        else:
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " hashing must be either explicitly or implicitly "
+                    "enabled."
+                )
+            builder.make_unhashable()
+
+        if init is True:
+            builder.add_init()
+        else:
+            if cache_hash:
+                raise TypeError(
+                    "Invalid value for cache_hash.  To use hash caching,"
+                    " init must be True."
+                )
+
+        return builder.build_class()
+
+    # maybe_cls's type depends on the usage of the decorator.  It's a class
+    # if it's used as `@attrs` but ``None`` if used as `@attrs()`.
+    if maybe_cls is None:
+        return wrap
+    else:
+        return wrap(maybe_cls)
+
+
+_attrs = attrs
+"""
+Internal alias so we can use it in functions that take an argument called
+*attrs*.
+"""
+
+
+if PY2:
+
+    def _has_frozen_base_class(cls):
+        """
+        Check whether *cls* has a frozen ancestor by looking at its
+        __setattr__.
+        """
+        return (
+            getattr(cls.__setattr__, "__module__", None)
+            == _frozen_setattrs.__module__
+            and cls.__setattr__.__name__ == _frozen_setattrs.__name__
+        )
+
+
+else:
+
+    def _has_frozen_base_class(cls):
+        """
+        Check whether *cls* has a frozen ancestor by looking at its
+        __setattr__.
+        """
+        return cls.__setattr__ == _frozen_setattrs
+
+
+def _attrs_to_tuple(obj, attrs):
+    """
+    Create a tuple of all values of *obj*'s *attrs*.
+    """
+    return tuple(getattr(obj, a.name) for a in attrs)
+
+
+def _make_hash(attrs, frozen, cache_hash):
+    attrs = tuple(
+        a
+        for a in attrs
+        if a.hash is True or (a.hash is None and a.cmp is True)
+    )
+
+    tab = "        "
+
+    # We cache the generated hash methods for the same kinds of attributes.
+    sha1 = hashlib.sha1()
+    sha1.update(repr(attrs).encode("utf-8"))
+    unique_filename = "<attrs generated hash %s>" % (sha1.hexdigest(),)
+    type_hash = hash(unique_filename)
+
+    method_lines = ["def __hash__(self):"]
+
+    def append_hash_computation_lines(prefix, indent):
+        """
+        Generate the code for actually computing the hash code.
+        Below this will either be returned directly or used to compute
+        a value which is then cached, depending on the value of cache_hash
+        """
+        method_lines.extend(
+            [indent + prefix + "hash((", indent + "        %d," % (type_hash,)]
+        )
+
+        for a in attrs:
+            method_lines.append(indent + "        self.%s," % a.name)
+
+        method_lines.append(indent + "    ))")
+
+    if cache_hash:
+        method_lines.append(tab + "if self.%s is None:" % _hash_cache_field)
+        if frozen:
+            append_hash_computation_lines(
+                "object.__setattr__(self, '%s', " % _hash_cache_field, tab * 2
+            )
+            method_lines.append(tab * 2 + ")")  # close __setattr__
+        else:
+            append_hash_computation_lines(
+                "self.%s = " % _hash_cache_field, tab * 2
+            )
+        method_lines.append(tab + "return self.%s" % _hash_cache_field)
+    else:
+        append_hash_computation_lines("return ", tab)
+
+    script = "\n".join(method_lines)
+    globs = {}
+    locs = {}
+    bytecode = compile(script, unique_filename, "exec")
+    eval(bytecode, globs, locs)
+
+    # In order of debuggers like PDB being able to step through the code,
+    # we add a fake linecache entry.
+    linecache.cache[unique_filename] = (
+        len(script),
+        None,
+        script.splitlines(True),
+        unique_filename,
+    )
+
+    return locs["__hash__"]
+
+
+def _add_hash(cls, attrs):
+    """
+    Add a hash method to *cls*.
+    """
+    cls.__hash__ = _make_hash(attrs, frozen=False, cache_hash=False)
+    return cls
+
+
+def __ne__(self, other):
+    """
+    Check equality and either forward a NotImplemented or return the result
+    negated.
+    """
+    result = self.__eq__(other)
+    if result is NotImplemented:
+        return NotImplemented
+
+    return not result
+
+
+WARNING_CMP_ISINSTANCE = (
+    "Comparision of subclasses using __%s__ is deprecated and will be removed "
+    "in 2019."
+)
+
+
+def _make_cmp(attrs):
+    attrs = [a for a in attrs if a.cmp]
+
+    # We cache the generated eq methods for the same kinds of attributes.
+    sha1 = hashlib.sha1()
+    sha1.update(repr(attrs).encode("utf-8"))
+    unique_filename = "<attrs generated eq %s>" % (sha1.hexdigest(),)
+    lines = [
+        "def __eq__(self, other):",
+        "    if other.__class__ is not self.__class__:",
+        "        return NotImplemented",
+    ]
+    # We can't just do a big self.x = other.x and... clause due to
+    # irregularities like nan == nan is false but (nan,) == (nan,) is true.
+    if attrs:
+        lines.append("    return  (")
+        others = ["    ) == ("]
+        for a in attrs:
+            lines.append("        self.%s," % (a.name,))
+            others.append("        other.%s," % (a.name,))
+
+        lines += others + ["    )"]
+    else:
+        lines.append("    return True")
+
+    script = "\n".join(lines)
+    globs = {}
+    locs = {}
+    bytecode = compile(script, unique_filename, "exec")
+    eval(bytecode, globs, locs)
+
+    # In order of debuggers like PDB being able to step through the code,
+    # we add a fake linecache entry.
+    linecache.cache[unique_filename] = (
+        len(script),
+        None,
+        script.splitlines(True),
+        unique_filename,
+    )
+    eq = locs["__eq__"]
+    ne = __ne__
+
+    def attrs_to_tuple(obj):
+        """
+        Save us some typing.
+        """
+        return _attrs_to_tuple(obj, attrs)
+
+    def __lt__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            if other.__class__ is not self.__class__:
+                warnings.warn(
+                    WARNING_CMP_ISINSTANCE % ("lt",), DeprecationWarning
+                )
+            return attrs_to_tuple(self) < attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def __le__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            if other.__class__ is not self.__class__:
+                warnings.warn(
+                    WARNING_CMP_ISINSTANCE % ("le",), DeprecationWarning
+                )
+            return attrs_to_tuple(self) <= attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def __gt__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            if other.__class__ is not self.__class__:
+                warnings.warn(
+                    WARNING_CMP_ISINSTANCE % ("gt",), DeprecationWarning
+                )
+            return attrs_to_tuple(self) > attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    def __ge__(self, other):
+        """
+        Automatically created by attrs.
+        """
+        if isinstance(other, self.__class__):
+            if other.__class__ is not self.__class__:
+                warnings.warn(
+                    WARNING_CMP_ISINSTANCE % ("ge",), DeprecationWarning
+                )
+            return attrs_to_tuple(self) >= attrs_to_tuple(other)
+        else:
+            return NotImplemented
+
+    return eq, ne, __lt__, __le__, __gt__, __ge__
+
+
+def _add_cmp(cls, attrs=None):
+    """
+    Add comparison methods to *cls*.
+    """
+    if attrs is None:
+        attrs = cls.__attrs_attrs__
+
+    cls.__eq__, cls.__ne__, cls.__lt__, cls.__le__, cls.__gt__, cls.__ge__ = _make_cmp(  # noqa
+        attrs
+    )
+
+    return cls
+
+
+_already_repring = threading.local()
+
+
+def _make_repr(attrs, ns):
+    """
+    Make a repr method for *attr_names* adding *ns* to the full name.
+    """
+    attr_names = tuple(a.name for a in attrs if a.repr)
+
+    def __repr__(self):
+        """
+        Automatically created by attrs.
+        """
+        try:
+            working_set = _already_repring.working_set
+        except AttributeError:
+            working_set = set()
+            _already_repring.working_set = working_set
+
+        if id(self) in working_set:
+            return "..."
+        real_cls = self.__class__
+        if ns is None:
+            qualname = getattr(real_cls, "__qualname__", None)
+            if qualname is not None:
+                class_name = qualname.rsplit(">.", 1)[-1]
+            else:
+                class_name = real_cls.__name__
+        else:
+            class_name = ns + "." + real_cls.__name__
+
+        # Since 'self' remains on the stack (i.e.: strongly referenced) for the
+        # duration of this call, it's safe to depend on id(...) stability, and
+        # not need to track the instance and therefore worry about properties
+        # like weakref- or hash-ability.
+        working_set.add(id(self))
+        try:
+            result = [class_name, "("]
+            first = True
+            for name in attr_names:
+                if first:
+                    first = False
+                else:
+                    result.append(", ")
+                result.extend((name, "=", repr(getattr(self, name, NOTHING))))
+            return "".join(result) + ")"
+        finally:
+            working_set.remove(id(self))
+
+    return __repr__
+
+
+def _add_repr(cls, ns=None, attrs=None):
+    """
+    Add a repr method to *cls*.
+    """
+    if attrs is None:
+        attrs = cls.__attrs_attrs__
+
+    cls.__repr__ = _make_repr(attrs, ns)
+    return cls
+
+
+def _make_init(attrs, post_init, frozen, slots, cache_hash, base_attr_map):
+    attrs = [a for a in attrs if a.init or a.default is not NOTHING]
+
+    # We cache the generated init methods for the same kinds of attributes.
+    sha1 = hashlib.sha1()
+    sha1.update(repr(attrs).encode("utf-8"))
+    unique_filename = "<attrs generated init {0}>".format(sha1.hexdigest())
+
+    script, globs, annotations = _attrs_to_init_script(
+        attrs, frozen, slots, post_init, cache_hash, base_attr_map
+    )
+    locs = {}
+    bytecode = compile(script, unique_filename, "exec")
+    attr_dict = dict((a.name, a) for a in attrs)
+    globs.update({"NOTHING": NOTHING, "attr_dict": attr_dict})
+    if frozen is True:
+        # Save the lookup overhead in __init__ if we need to circumvent
+        # immutability.
+        globs["_cached_setattr"] = _obj_setattr
+    eval(bytecode, globs, locs)
+
+    # In order of debuggers like PDB being able to step through the code,
+    # we add a fake linecache entry.
+    linecache.cache[unique_filename] = (
+        len(script),
+        None,
+        script.splitlines(True),
+        unique_filename,
+    )
+
+    __init__ = locs["__init__"]
+    __init__.__annotations__ = annotations
+    return __init__
+
+
+def _add_init(cls, frozen):
+    """
+    Add a __init__ method to *cls*.  If *frozen* is True, make it immutable.
+    """
+    cls.__init__ = _make_init(
+        cls.__attrs_attrs__,
+        getattr(cls, "__attrs_post_init__", False),
+        frozen,
+        _is_slot_cls(cls),
+        cache_hash=False,
+        base_attr_map={},
+    )
+    return cls
+
+
+def fields(cls):
+    """
+    Return the tuple of ``attrs`` attributes for a class.
+
+    The tuple also allows accessing the fields by their names (see below for
+    examples).
+
+    :param type cls: Class to introspect.
+
+    :raise TypeError: If *cls* is not a class.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    :rtype: tuple (with name accessors) of :class:`attr.Attribute`
+
+    ..  versionchanged:: 16.2.0 Returned tuple allows accessing the fields
+        by name.
+    """
+    if not isclass(cls):
+        raise TypeError("Passed object must be a class.")
+    attrs = getattr(cls, "__attrs_attrs__", None)
+    if attrs is None:
+        raise NotAnAttrsClassError(
+            "{cls!r} is not an attrs-decorated class.".format(cls=cls)
+        )
+    return attrs
+
+
+def fields_dict(cls):
+    """
+    Return an ordered dictionary of ``attrs`` attributes for a class, whose
+    keys are the attribute names.
+
+    :param type cls: Class to introspect.
+
+    :raise TypeError: If *cls* is not a class.
+    :raise attr.exceptions.NotAnAttrsClassError: If *cls* is not an ``attrs``
+        class.
+
+    :rtype: an ordered dict where keys are attribute names and values are
+        :class:`attr.Attribute`\\ s. This will be a :class:`dict` if it's
+        naturally ordered like on Python 3.6+ or an
+        :class:`~collections.OrderedDict` otherwise.
+
+    .. versionadded:: 18.1.0
+    """
+    if not isclass(cls):
+        raise TypeError("Passed object must be a class.")
+    attrs = getattr(cls, "__attrs_attrs__", None)
+    if attrs is None:
+        raise NotAnAttrsClassError(
+            "{cls!r} is not an attrs-decorated class.".format(cls=cls)
+        )
+    return ordered_dict(((a.name, a) for a in attrs))
+
+
+def validate(inst):
+    """
+    Validate all attributes on *inst* that have a validator.
+
+    Leaves all exceptions through.
+
+    :param inst: Instance of a class with ``attrs`` attributes.
+    """
+    if _config._run_validators is False:
+        return
+
+    for a in fields(inst.__class__):
+        v = a.validator
+        if v is not None:
+            v(inst, a, getattr(inst, a.name))
+
+
+def _is_slot_cls(cls):
+    return "__slots__" in cls.__dict__
+
+
+def _is_slot_attr(a_name, base_attr_map):
+    """
+    Check if the attribute name comes from a slot class.
+    """
+    return a_name in base_attr_map and _is_slot_cls(base_attr_map[a_name])
+
+
+def _attrs_to_init_script(
+    attrs, frozen, slots, post_init, cache_hash, base_attr_map
+):
+    """
+    Return a script of an initializer for *attrs* and a dict of globals.
+
+    The globals are expected by the generated script.
+
+    If *frozen* is True, we cannot set the attributes directly so we use
+    a cached ``object.__setattr__``.
+    """
+    lines = []
+    any_slot_ancestors = any(
+        _is_slot_attr(a.name, base_attr_map) for a in attrs
+    )
+    if frozen is True:
+        if slots is True:
+            lines.append(
+                # Circumvent the __setattr__ descriptor to save one lookup per
+                # assignment.
+                # Note _setattr will be used again below if cache_hash is True
+                "_setattr = _cached_setattr.__get__(self, self.__class__)"
+            )
+
+            def fmt_setter(attr_name, value_var):
+                return "_setattr('%(attr_name)s', %(value_var)s)" % {
+                    "attr_name": attr_name,
+                    "value_var": value_var,
+                }
+
+            def fmt_setter_with_converter(attr_name, value_var):
+                conv_name = _init_converter_pat.format(attr_name)
+                return "_setattr('%(attr_name)s', %(conv)s(%(value_var)s))" % {
+                    "attr_name": attr_name,
+                    "value_var": value_var,
+                    "conv": conv_name,
+                }
+
+        else:
+            # Dict frozen classes assign directly to __dict__.
+            # But only if the attribute doesn't come from an ancestor slot
+            # class.
+            # Note _inst_dict will be used again below if cache_hash is True
+            lines.append("_inst_dict = self.__dict__")
+            if any_slot_ancestors:
+                lines.append(
+                    # Circumvent the __setattr__ descriptor to save one lookup
+                    # per assignment.
+                    "_setattr = _cached_setattr.__get__(self, self.__class__)"
+                )
+
+            def fmt_setter(attr_name, value_var):
+                if _is_slot_attr(attr_name, base_attr_map):
+                    res = "_setattr('%(attr_name)s', %(value_var)s)" % {
+                        "attr_name": attr_name,
+                        "value_var": value_var,
+                    }
+                else:
+                    res = "_inst_dict['%(attr_name)s'] = %(value_var)s" % {
+                        "attr_name": attr_name,
+                        "value_var": value_var,
+                    }
+                return res
+
+            def fmt_setter_with_converter(attr_name, value_var):
+                conv_name = _init_converter_pat.format(attr_name)
+                if _is_slot_attr(attr_name, base_attr_map):
+                    tmpl = "_setattr('%(attr_name)s', %(c)s(%(value_var)s))"
+                else:
+                    tmpl = "_inst_dict['%(attr_name)s'] = %(c)s(%(value_var)s)"
+                return tmpl % {
+                    "attr_name": attr_name,
+                    "value_var": value_var,
+                    "c": conv_name,
+                }
+
+    else:
+        # Not frozen.
+        def fmt_setter(attr_name, value):
+            return "self.%(attr_name)s = %(value)s" % {
+                "attr_name": attr_name,
+                "value": value,
+            }
+
+        def fmt_setter_with_converter(attr_name, value_var):
+            conv_name = _init_converter_pat.format(attr_name)
+            return "self.%(attr_name)s = %(conv)s(%(value_var)s)" % {
+                "attr_name": attr_name,
+                "value_var": value_var,
+                "conv": conv_name,
+            }
+
+    args = []
+    kw_only_args = []
+    attrs_to_validate = []
+
+    # This is a dictionary of names to validator and converter callables.
+    # Injecting this into __init__ globals lets us avoid lookups.
+    names_for_globals = {}
+    annotations = {"return": None}
+
+    for a in attrs:
+        if a.validator:
+            attrs_to_validate.append(a)
+        attr_name = a.name
+        arg_name = a.name.lstrip("_")
+        has_factory = isinstance(a.default, Factory)
+        if has_factory and a.default.takes_self:
+            maybe_self = "self"
+        else:
+            maybe_self = ""
+        if a.init is False:
+            if has_factory:
+                init_factory_name = _init_factory_pat.format(a.name)
+                if a.converter is not None:
+                    lines.append(
+                        fmt_setter_with_converter(
+                            attr_name,
+                            init_factory_name + "({0})".format(maybe_self),
+                        )
+                    )
+                    conv_name = _init_converter_pat.format(a.name)
+                    names_for_globals[conv_name] = a.converter
+                else:
+                    lines.append(
+                        fmt_setter(
+                            attr_name,
+                            init_factory_name + "({0})".format(maybe_self),
+                        )
+                    )
+                names_for_globals[init_factory_name] = a.default.factory
+            else:
+                if a.converter is not None:
+                    lines.append(
+                        fmt_setter_with_converter(
+                            attr_name,
+                            "attr_dict['{attr_name}'].default".format(
+                                attr_name=attr_name
+                            ),
+                        )
+                    )
+                    conv_name = _init_converter_pat.format(a.name)
+                    names_for_globals[conv_name] = a.converter
+                else:
+                    lines.append(
+                        fmt_setter(
+                            attr_name,
+                            "attr_dict['{attr_name}'].default".format(
+                                attr_name=attr_name
+                            ),
+                        )
+                    )
+        elif a.default is not NOTHING and not has_factory:
+            arg = "{arg_name}=attr_dict['{attr_name}'].default".format(
+                arg_name=arg_name, attr_name=attr_name
+            )
+            if a.kw_only:
+                kw_only_args.append(arg)
+            else:
+                args.append(arg)
+            if a.converter is not None:
+                lines.append(fmt_setter_with_converter(attr_name, arg_name))
+                names_for_globals[
+                    _init_converter_pat.format(a.name)
+                ] = a.converter
+            else:
+                lines.append(fmt_setter(attr_name, arg_name))
+        elif has_factory:
+            arg = "{arg_name}=NOTHING".format(arg_name=arg_name)
+            if a.kw_only:
+                kw_only_args.append(arg)
+            else:
+                args.append(arg)
+            lines.append(
+                "if {arg_name} is not NOTHING:".format(arg_name=arg_name)
+            )
+            init_factory_name = _init_factory_pat.format(a.name)
+            if a.converter is not None:
+                lines.append(
+                    "    " + fmt_setter_with_converter(attr_name, arg_name)
+                )
+                lines.append("else:")
+                lines.append(
+                    "    "
+                    + fmt_setter_with_converter(
+                        attr_name,
+                        init_factory_name + "({0})".format(maybe_self),
+                    )
+                )
+                names_for_globals[
+                    _init_converter_pat.format(a.name)
+                ] = a.converter
+            else:
+                lines.append("    " + fmt_setter(attr_name, arg_name))
+                lines.append("else:")
+                lines.append(
+                    "    "
+                    + fmt_setter(
+                        attr_name,
+                        init_factory_name + "({0})".format(maybe_self),
+                    )
+                )
+            names_for_globals[init_factory_name] = a.default.factory
+        else:
+            if a.kw_only:
+                kw_only_args.append(arg_name)
+            else:
+                args.append(arg_name)
+            if a.converter is not None:
+                lines.append(fmt_setter_with_converter(attr_name, arg_name))
+                names_for_globals[
+                    _init_converter_pat.format(a.name)
+                ] = a.converter
+            else:
+                lines.append(fmt_setter(attr_name, arg_name))
+
+        if a.init is True and a.converter is None and a.type is not None:
+            annotations[arg_name] = a.type
+
+    if attrs_to_validate:  # we can skip this if there are no validators.
+        names_for_globals["_config"] = _config
+        lines.append("if _config._run_validators is True:")
+        for a in attrs_to_validate:
+            val_name = "__attr_validator_{}".format(a.name)
+            attr_name = "__attr_{}".format(a.name)
+            lines.append(
+                "    {}(self, {}, self.{})".format(val_name, attr_name, a.name)
+            )
+            names_for_globals[val_name] = a.validator
+            names_for_globals[attr_name] = a
+    if post_init:
+        lines.append("self.__attrs_post_init__()")
+
+    # because this is set only after __attrs_post_init is called, a crash
+    # will result if post-init tries to access the hash code.  This seemed
+    # preferable to setting this beforehand, in which case alteration to
+    # field values during post-init combined with post-init accessing the
+    # hash code would result in silent bugs.
+    if cache_hash:
+        if frozen:
+            if slots:
+                # if frozen and slots, then _setattr defined above
+                init_hash_cache = "_setattr('%s', %s)"
+            else:
+                # if frozen and not slots, then _inst_dict defined above
+                init_hash_cache = "_inst_dict['%s'] = %s"
+        else:
+            init_hash_cache = "self.%s = %s"
+        lines.append(init_hash_cache % (_hash_cache_field, "None"))
+
+    args = ", ".join(args)
+    if kw_only_args:
+        if PY2:
+            raise PythonTooOldError(
+                "Keyword-only arguments only work on Python 3 and later."
+            )
+
+        args += "{leading_comma}*, {kw_only_args}".format(
+            leading_comma=", " if args else "",
+            kw_only_args=", ".join(kw_only_args),
+        )
+    return (
+        """\
+def __init__(self, {args}):
+    {lines}
+""".format(
+            args=args, lines="\n    ".join(lines) if lines else "pass"
+        ),
+        names_for_globals,
+        annotations,
+    )
+
+
+class Attribute(object):
+    """
+    *Read-only* representation of an attribute.
+
+    :attribute name: The name of the attribute.
+
+    Plus *all* arguments of :func:`attr.ib`.
+
+    For the version history of the fields, see :func:`attr.ib`.
+    """
+
+    __slots__ = (
+        "name",
+        "default",
+        "validator",
+        "repr",
+        "cmp",
+        "hash",
+        "init",
+        "metadata",
+        "type",
+        "converter",
+        "kw_only",
+    )
+
+    def __init__(
+        self,
+        name,
+        default,
+        validator,
+        repr,
+        cmp,
+        hash,
+        init,
+        convert=None,
+        metadata=None,
+        type=None,
+        converter=None,
+        kw_only=False,
+    ):
+        # Cache this descriptor here to speed things up later.
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+
+        # Despite the big red warning, people *do* instantiate `Attribute`
+        # themselves.
+        if convert is not None:
+            if converter is not None:
+                raise RuntimeError(
+                    "Can't pass both `convert` and `converter`.  "
+                    "Please use `converter` only."
+                )
+            warnings.warn(
+                "The `convert` argument is deprecated in favor of `converter`."
+                "  It will be removed after 2019/01.",
+                DeprecationWarning,
+                stacklevel=2,
+            )
+            converter = convert
+
+        bound_setattr("name", name)
+        bound_setattr("default", default)
+        bound_setattr("validator", validator)
+        bound_setattr("repr", repr)
+        bound_setattr("cmp", cmp)
+        bound_setattr("hash", hash)
+        bound_setattr("init", init)
+        bound_setattr("converter", converter)
+        bound_setattr(
+            "metadata",
+            (
+                metadata_proxy(metadata)
+                if metadata
+                else _empty_metadata_singleton
+            ),
+        )
+        bound_setattr("type", type)
+        bound_setattr("kw_only", kw_only)
+
+    def __setattr__(self, name, value):
+        raise FrozenInstanceError()
+
+    @property
+    def convert(self):
+        warnings.warn(
+            "The `convert` attribute is deprecated in favor of `converter`.  "
+            "It will be removed after 2019/01.",
+            DeprecationWarning,
+            stacklevel=2,
+        )
+        return self.converter
+
+    @classmethod
+    def from_counting_attr(cls, name, ca, type=None):
+        # type holds the annotated value. deal with conflicts:
+        if type is None:
+            type = ca.type
+        elif ca.type is not None:
+            raise ValueError(
+                "Type annotation and type argument cannot both be present"
+            )
+        inst_dict = {
+            k: getattr(ca, k)
+            for k in Attribute.__slots__
+            if k
+            not in (
+                "name",
+                "validator",
+                "default",
+                "type",
+                "convert",
+            )  # exclude methods and deprecated alias
+        }
+        return cls(
+            name=name,
+            validator=ca._validator,
+            default=ca._default,
+            type=type,
+            **inst_dict
+        )
+
+    # Don't use attr.assoc since fields(Attribute) doesn't work
+    def _assoc(self, **changes):
+        """
+        Copy *self* and apply *changes*.
+        """
+        new = copy.copy(self)
+
+        new._setattrs(changes.items())
+
+        return new
+
+    # Don't use _add_pickle since fields(Attribute) doesn't work
+    def __getstate__(self):
+        """
+        Play nice with pickle.
+        """
+        return tuple(
+            getattr(self, name) if name != "metadata" else dict(self.metadata)
+            for name in self.__slots__
+        )
+
+    def __setstate__(self, state):
+        """
+        Play nice with pickle.
+        """
+        self._setattrs(zip(self.__slots__, state))
+
+    def _setattrs(self, name_values_pairs):
+        bound_setattr = _obj_setattr.__get__(self, Attribute)
+        for name, value in name_values_pairs:
+            if name != "metadata":
+                bound_setattr(name, value)
+            else:
+                bound_setattr(
+                    name,
+                    metadata_proxy(value)
+                    if value
+                    else _empty_metadata_singleton,
+                )
+
+
+_a = [
+    Attribute(
+        name=name,
+        default=NOTHING,
+        validator=None,
+        repr=True,
+        cmp=True,
+        hash=(name != "metadata"),
+        init=True,
+    )
+    for name in Attribute.__slots__
+    if name != "convert"  # XXX: remove once `convert` is gone
+]
+
+Attribute = _add_hash(
+    _add_cmp(_add_repr(Attribute, attrs=_a), attrs=_a),
+    attrs=[a for a in _a if a.hash],
+)
+
+
+class _CountingAttr(object):
+    """
+    Intermediate representation of attributes that uses a counter to preserve
+    the order in which the attributes have been defined.
+
+    *Internal* data structure of the attrs library.  Running into is most
+    likely the result of a bug like a forgotten `@attr.s` decorator.
+    """
+
+    __slots__ = (
+        "counter",
+        "_default",
+        "repr",
+        "cmp",
+        "hash",
+        "init",
+        "metadata",
+        "_validator",
+        "converter",
+        "type",
+        "kw_only",
+    )
+    __attrs_attrs__ = tuple(
+        Attribute(
+            name=name,
+            default=NOTHING,
+            validator=None,
+            repr=True,
+            cmp=True,
+            hash=True,
+            init=True,
+            kw_only=False,
+        )
+        for name in ("counter", "_default", "repr", "cmp", "hash", "init")
+    ) + (
+        Attribute(
+            name="metadata",
+            default=None,
+            validator=None,
+            repr=True,
+            cmp=True,
+            hash=False,
+            init=True,
+            kw_only=False,
+        ),
+    )
+    cls_counter = 0
+
+    def __init__(
+        self,
+        default,
+        validator,
+        repr,
+        cmp,
+        hash,
+        init,
+        converter,
+        metadata,
+        type,
+        kw_only,
+    ):
+        _CountingAttr.cls_counter += 1
+        self.counter = _CountingAttr.cls_counter
+        self._default = default
+        # If validator is a list/tuple, wrap it using helper validator.
+        if validator and isinstance(validator, (list, tuple)):
+            self._validator = and_(*validator)
+        else:
+            self._validator = validator
+        self.repr = repr
+        self.cmp = cmp
+        self.hash = hash
+        self.init = init
+        self.converter = converter
+        self.metadata = metadata
+        self.type = type
+        self.kw_only = kw_only
+
+    def validator(self, meth):
+        """
+        Decorator that adds *meth* to the list of validators.
+
+        Returns *meth* unchanged.
+
+        .. versionadded:: 17.1.0
+        """
+        if self._validator is None:
+            self._validator = meth
+        else:
+            self._validator = and_(self._validator, meth)
+        return meth
+
+    def default(self, meth):
+        """
+        Decorator that allows to set the default for an attribute.
+
+        Returns *meth* unchanged.
+
+        :raises DefaultAlreadySetError: If default has been set before.
+
+        .. versionadded:: 17.1.0
+        """
+        if self._default is not NOTHING:
+            raise DefaultAlreadySetError()
+
+        self._default = Factory(meth, takes_self=True)
+
+        return meth
+
+
+_CountingAttr = _add_cmp(_add_repr(_CountingAttr))
+
+
+@attrs(slots=True, init=False, hash=True)
+class Factory(object):
+    """
+    Stores a factory callable.
+
+    If passed as the default value to :func:`attr.ib`, the factory is used to
+    generate a new value.
+
+    :param callable factory: A callable that takes either none or exactly one
+        mandatory positional argument depending on *takes_self*.
+    :param bool takes_self: Pass the partially initialized instance that is
+        being initialized as a positional argument.
+
+    .. versionadded:: 17.1.0  *takes_self*
+    """
+
+    factory = attrib()
+    takes_self = attrib()
+
+    def __init__(self, factory, takes_self=False):
+        """
+        `Factory` is part of the default machinery so if we want a default
+        value here, we have to implement it ourselves.
+        """
+        self.factory = factory
+        self.takes_self = takes_self
+
+
+def make_class(name, attrs, bases=(object,), **attributes_arguments):
+    """
+    A quick way to create a new class called *name* with *attrs*.
+
+    :param name: The name for the new class.
+    :type name: str
+
+    :param attrs: A list of names or a dictionary of mappings of names to
+        attributes.
+
+        If *attrs* is a list or an ordered dict (:class:`dict` on Python 3.6+,
+        :class:`collections.OrderedDict` otherwise), the order is deduced from
+        the order of the names or attributes inside *attrs*.  Otherwise the
+        order of the definition of the attributes is used.
+    :type attrs: :class:`list` or :class:`dict`
+
+    :param tuple bases: Classes that the new class will subclass.
+
+    :param attributes_arguments: Passed unmodified to :func:`attr.s`.
+
+    :return: A new class with *attrs*.
+    :rtype: type
+
+    .. versionadded:: 17.1.0 *bases*
+    .. versionchanged:: 18.1.0 If *attrs* is ordered, the order is retained.
+    """
+    if isinstance(attrs, dict):
+        cls_dict = attrs
+    elif isinstance(attrs, (list, tuple)):
+        cls_dict = dict((a, attrib()) for a in attrs)
+    else:
+        raise TypeError("attrs argument must be a dict or a list.")
+
+    post_init = cls_dict.pop("__attrs_post_init__", None)
+    type_ = type(
+        name,
+        bases,
+        {} if post_init is None else {"__attrs_post_init__": post_init},
+    )
+    # For pickling to work, the __module__ variable needs to be set to the
+    # frame where the class is created.  Bypass this step in environments where
+    # sys._getframe is not defined (Jython for example) or sys._getframe is not
+    # defined for arguments greater than 0 (IronPython).
+    try:
+        type_.__module__ = sys._getframe(1).f_globals.get(
+            "__name__", "__main__"
+        )
+    except (AttributeError, ValueError):
+        pass
+
+    return _attrs(these=cls_dict, **attributes_arguments)(type_)
+
+
+# These are required by within this module so we define them here and merely
+# import into .validators.
+
+
+@attrs(slots=True, hash=True)
+class _AndValidator(object):
+    """
+    Compose many validators to a single one.
+    """
+
+    _validators = attrib()
+
+    def __call__(self, inst, attr, value):
+        for v in self._validators:
+            v(inst, attr, value)
+
+
+def and_(*validators):
+    """
+    A validator that composes multiple validators into one.
+
+    When called on a value, it runs all wrapped validators.
+
+    :param validators: Arbitrary number of validators.
+    :type validators: callables
+
+    .. versionadded:: 17.1.0
+    """
+    vals = []
+    for validator in validators:
+        vals.extend(
+            validator._validators
+            if isinstance(validator, _AndValidator)
+            else [validator]
+        )
+
+    return _AndValidator(tuple(vals))
diff --git a/python/attr/converters.py b/python/attr/converters.py
new file mode 100644
index 0000000..37c4a07
--- /dev/null
+++ b/python/attr/converters.py
@@ -0,0 +1,78 @@
+"""
+Commonly useful converters.
+"""
+
+from __future__ import absolute_import, division, print_function
+
+from ._make import NOTHING, Factory
+
+
+def optional(converter):
+    """
+    A converter that allows an attribute to be optional. An optional attribute
+    is one which can be set to ``None``.
+
+    :param callable converter: the converter that is used for non-``None``
+        values.
+
+    .. versionadded:: 17.1.0
+    """
+
+    def optional_converter(val):
+        if val is None:
+            return None
+        return converter(val)
+
+    return optional_converter
+
+
+def default_if_none(default=NOTHING, factory=None):
+    """
+    A converter that allows to replace ``None`` values by *default* or the
+    result of *factory*.
+
+    :param default: Value to be used if ``None`` is passed. Passing an instance
+       of :class:`attr.Factory` is supported, however the ``takes_self`` option
+       is *not*.
+    :param callable factory: A callable that takes not parameters whose result
+       is used if ``None`` is passed.
+
+    :raises TypeError: If **neither** *default* or *factory* is passed.
+    :raises TypeError: If **both** *default* and *factory* are passed.
+    :raises ValueError: If an instance of :class:`attr.Factory` is passed with
+       ``takes_self=True``.
+
+    .. versionadded:: 18.2.0
+    """
+    if default is NOTHING and factory is None:
+        raise TypeError("Must pass either `default` or `factory`.")
+
+    if default is not NOTHING and factory is not None:
+        raise TypeError(
+            "Must pass either `default` or `factory` but not both."
+        )
+
+    if factory is not None:
+        default = Factory(factory)
+
+    if isinstance(default, Factory):
+        if default.takes_self:
+            raise ValueError(
+                "`takes_self` is not supported by default_if_none."
+            )
+
+        def default_if_none_converter(val):
+            if val is not None:
+                return val
+
+            return default.factory()
+
+    else:
+
+        def default_if_none_converter(val):
+            if val is not None:
+                return val
+
+            return default
+
+    return default_if_none_converter
diff --git a/python/attr/converters.pyi b/python/attr/converters.pyi
new file mode 100644
index 0000000..63b2a38
--- /dev/null
+++ b/python/attr/converters.pyi
@@ -0,0 +1,12 @@
+from typing import TypeVar, Optional, Callable, overload
+from . import _ConverterType
+
+_T = TypeVar("_T")
+
+def optional(
+    converter: _ConverterType[_T]
+) -> _ConverterType[Optional[_T]]: ...
+@overload
+def default_if_none(default: _T) -> _ConverterType[_T]: ...
+@overload
+def default_if_none(*, factory: Callable[[], _T]) -> _ConverterType[_T]: ...
diff --git a/python/attr/exceptions.py b/python/attr/exceptions.py
new file mode 100644
index 0000000..b12e41e
--- /dev/null
+++ b/python/attr/exceptions.py
@@ -0,0 +1,57 @@
+from __future__ import absolute_import, division, print_function
+
+
+class FrozenInstanceError(AttributeError):
+    """
+    A frozen/immutable instance has been attempted to be modified.
+
+    It mirrors the behavior of ``namedtuples`` by using the same error message
+    and subclassing :exc:`AttributeError`.
+
+    .. versionadded:: 16.1.0
+    """
+
+    msg = "can't set attribute"
+    args = [msg]
+
+
+class AttrsAttributeNotFoundError(ValueError):
+    """
+    An ``attrs`` function couldn't find an attribute that the user asked for.
+
+    .. versionadded:: 16.2.0
+    """
+
+
+class NotAnAttrsClassError(ValueError):
+    """
+    A non-``attrs`` class has been passed into an ``attrs`` function.
+
+    .. versionadded:: 16.2.0
+    """
+
+
+class DefaultAlreadySetError(RuntimeError):
+    """
+    A default has been set using ``attr.ib()`` and is attempted to be reset
+    using the decorator.
+
+    .. versionadded:: 17.1.0
+    """
+
+
+class UnannotatedAttributeError(RuntimeError):
+    """
+    A class with ``auto_attribs=True`` has an ``attr.ib()`` without a type
+    annotation.
+
+    .. versionadded:: 17.3.0
+    """
+
+
+class PythonTooOldError(RuntimeError):
+    """
+    An ``attrs`` feature requiring a more recent python version has been used.
+
+    .. versionadded:: 18.2.0
+    """
diff --git a/python/attr/exceptions.pyi b/python/attr/exceptions.pyi
new file mode 100644
index 0000000..48fffcc
--- /dev/null
+++ b/python/attr/exceptions.pyi
@@ -0,0 +1,7 @@
+class FrozenInstanceError(AttributeError):
+    msg: str = ...
+
+class AttrsAttributeNotFoundError(ValueError): ...
+class NotAnAttrsClassError(ValueError): ...
+class DefaultAlreadySetError(RuntimeError): ...
+class UnannotatedAttributeError(RuntimeError): ...
diff --git a/python/attr/filters.py b/python/attr/filters.py
new file mode 100644
index 0000000..f1c69b8
--- /dev/null
+++ b/python/attr/filters.py
@@ -0,0 +1,52 @@
+"""
+Commonly useful filters for :func:`attr.asdict`.
+"""
+
+from __future__ import absolute_import, division, print_function
+
+from ._compat import isclass
+from ._make import Attribute
+
+
+def _split_what(what):
+    """
+    Returns a tuple of `frozenset`s of classes and attributes.
+    """
+    return (
+        frozenset(cls for cls in what if isclass(cls)),
+        frozenset(cls for cls in what if isinstance(cls, Attribute)),
+    )
+
+
+def include(*what):
+    """
+    Whitelist *what*.
+
+    :param what: What to whitelist.
+    :type what: :class:`list` of :class:`type` or :class:`attr.Attribute`\\ s
+
+    :rtype: :class:`callable`
+    """
+    cls, attrs = _split_what(what)
+
+    def include_(attribute, value):
+        return value.__class__ in cls or attribute in attrs
+
+    return include_
+
+
+def exclude(*what):
+    """
+    Blacklist *what*.
+
+    :param what: What to blacklist.
+    :type what: :class:`list` of classes or :class:`attr.Attribute`\\ s.
+
+    :rtype: :class:`callable`
+    """
+    cls, attrs = _split_what(what)
+
+    def exclude_(attribute, value):
+        return value.__class__ not in cls and attribute not in attrs
+
+    return exclude_
diff --git a/python/attr/filters.pyi b/python/attr/filters.pyi
new file mode 100644
index 0000000..a618140
--- /dev/null
+++ b/python/attr/filters.pyi
@@ -0,0 +1,5 @@
+from typing import Union
+from . import Attribute, _FilterType
+
+def include(*what: Union[type, Attribute]) -> _FilterType: ...
+def exclude(*what: Union[type, Attribute]) -> _FilterType: ...
diff --git a/python/attr/py.typed b/python/attr/py.typed
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/python/attr/py.typed
diff --git a/python/attr/validators.py b/python/attr/validators.py
new file mode 100644
index 0000000..f12d0aa
--- /dev/null
+++ b/python/attr/validators.py
@@ -0,0 +1,170 @@
+"""
+Commonly useful validators.
+"""
+
+from __future__ import absolute_import, division, print_function
+
+from ._make import _AndValidator, and_, attrib, attrs
+
+
+__all__ = ["and_", "in_", "instance_of", "optional", "provides"]
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _InstanceOfValidator(object):
+    type = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not isinstance(value, self.type):
+            raise TypeError(
+                "'{name}' must be {type!r} (got {value!r} that is a "
+                "{actual!r}).".format(
+                    name=attr.name,
+                    type=self.type,
+                    actual=value.__class__,
+                    value=value,
+                ),
+                attr,
+                self.type,
+                value,
+            )
+
+    def __repr__(self):
+        return "<instance_of validator for type {type!r}>".format(
+            type=self.type
+        )
+
+
+def instance_of(type):
+    """
+    A validator that raises a :exc:`TypeError` if the initializer is called
+    with a wrong type for this particular attribute (checks are performed using
+    :func:`isinstance` therefore it's also valid to pass a tuple of types).
+
+    :param type: The type to check for.
+    :type type: type or tuple of types
+
+    :raises TypeError: With a human readable error message, the attribute
+        (of type :class:`attr.Attribute`), the expected type, and the value it
+        got.
+    """
+    return _InstanceOfValidator(type)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _ProvidesValidator(object):
+    interface = attrib()
+
+    def __call__(self, inst, attr, value):
+        """
+        We use a callable class to be able to change the ``__repr__``.
+        """
+        if not self.interface.providedBy(value):
+            raise TypeError(
+                "'{name}' must provide {interface!r} which {value!r} "
+                "doesn't.".format(
+                    name=attr.name, interface=self.interface, value=value
+                ),
+                attr,
+                self.interface,
+                value,
+            )
+
+    def __repr__(self):
+        return "<provides validator for interface {interface!r}>".format(
+            interface=self.interface
+        )
+
+
+def provides(interface):
+    """
+    A validator that raises a :exc:`TypeError` if the initializer is called
+    with an object that does not provide the requested *interface* (checks are
+    performed using ``interface.providedBy(value)`` (see `zope.interface
+    <https://zopeinterface.readthedocs.io/en/latest/>`_).
+
+    :param zope.interface.Interface interface: The interface to check for.
+
+    :raises TypeError: With a human readable error message, the attribute
+        (of type :class:`attr.Attribute`), the expected interface, and the
+        value it got.
+    """
+    return _ProvidesValidator(interface)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _OptionalValidator(object):
+    validator = attrib()
+
+    def __call__(self, inst, attr, value):
+        if value is None:
+            return
+
+        self.validator(inst, attr, value)
+
+    def __repr__(self):
+        return "<optional validator for {what} or None>".format(
+            what=repr(self.validator)
+        )
+
+
+def optional(validator):
+    """
+    A validator that makes an attribute optional.  An optional attribute is one
+    which can be set to ``None`` in addition to satisfying the requirements of
+    the sub-validator.
+
+    :param validator: A validator (or a list of validators) that is used for
+        non-``None`` values.
+    :type validator: callable or :class:`list` of callables.
+
+    .. versionadded:: 15.1.0
+    .. versionchanged:: 17.1.0 *validator* can be a list of validators.
+    """
+    if isinstance(validator, list):
+        return _OptionalValidator(_AndValidator(validator))
+    return _OptionalValidator(validator)
+
+
+@attrs(repr=False, slots=True, hash=True)
+class _InValidator(object):
+    options = attrib()
+
+    def __call__(self, inst, attr, value):
+        try:
+            in_options = value in self.options
+        except TypeError as e:  # e.g. `1 in "abc"`
+            in_options = False
+
+        if not in_options:
+            raise ValueError(
+                "'{name}' must be in {options!r} (got {value!r})".format(
+                    name=attr.name, options=self.options, value=value
+                )
+            )
+
+    def __repr__(self):
+        return "<in_ validator with options {options!r}>".format(
+            options=self.options
+        )
+
+
+def in_(options):
+    """
+    A validator that raises a :exc:`ValueError` if the initializer is called
+    with a value that does not belong in the options provided.  The check is
+    performed using ``value in options``.
+
+    :param options: Allowed options.
+    :type options: list, tuple, :class:`enum.Enum`, ...
+
+    :raises ValueError: With a human readable error message, the attribute (of
+       type :class:`attr.Attribute`), the expected options, and the value it
+       got.
+
+    .. versionadded:: 17.1.0
+    """
+    return _InValidator(options)
diff --git a/python/attr/validators.pyi b/python/attr/validators.pyi
new file mode 100644
index 0000000..abbaedf
--- /dev/null
+++ b/python/attr/validators.pyi
@@ -0,0 +1,14 @@
+from typing import Container, List, Union, TypeVar, Type, Any, Optional, Tuple
+from . import _ValidatorType
+
+_T = TypeVar("_T")
+
+def instance_of(
+    type: Union[Tuple[Type[_T], ...], Type[_T]]
+) -> _ValidatorType[_T]: ...
+def provides(interface: Any) -> _ValidatorType[Any]: ...
+def optional(
+    validator: Union[_ValidatorType[_T], List[_ValidatorType[_T]]]
+) -> _ValidatorType[Optional[_T]]: ...
+def in_(options: Container[_T]) -> _ValidatorType[_T]: ...
+def and_(*validators: _ValidatorType[_T]) -> _ValidatorType[_T]: ...
diff --git a/python/dateutil/__init__.py b/python/dateutil/__init__.py
new file mode 100644
index 0000000..796ef3d
--- /dev/null
+++ b/python/dateutil/__init__.py
@@ -0,0 +1,2 @@
+# -*- coding: utf-8 -*-
+from ._version import VERSION as __version__
diff --git a/python/dateutil/_common.py b/python/dateutil/_common.py
new file mode 100644
index 0000000..e8b4af7
--- /dev/null
+++ b/python/dateutil/_common.py
@@ -0,0 +1,34 @@
+"""
+Common code used in multiple modules.
+"""
+
+
+class weekday(object):
+    __slots__ = ["weekday", "n"]
+
+    def __init__(self, weekday, n=None):
+        self.weekday = weekday
+        self.n = n
+
+    def __call__(self, n):
+        if n == self.n:
+            return self
+        else:
+            return self.__class__(self.weekday, n)
+
+    def __eq__(self, other):
+        try:
+            if self.weekday != other.weekday or self.n != other.n:
+                return False
+        except AttributeError:
+            return False
+        return True
+
+    __hash__ = None
+
+    def __repr__(self):
+        s = ("MO", "TU", "WE", "TH", "FR", "SA", "SU")[self.weekday]
+        if not self.n:
+            return s
+        else:
+            return "%s(%+d)" % (s, self.n)
diff --git a/python/dateutil/_version.py b/python/dateutil/_version.py
new file mode 100644
index 0000000..c1a0357
--- /dev/null
+++ b/python/dateutil/_version.py
@@ -0,0 +1,10 @@
+"""
+Contains information about the dateutil version.
+"""
+
+VERSION_MAJOR = 2
+VERSION_MINOR = 6
+VERSION_PATCH = 1
+
+VERSION_TUPLE = (VERSION_MAJOR, VERSION_MINOR, VERSION_PATCH)
+VERSION = '.'.join(map(str, VERSION_TUPLE))
diff --git a/python/dateutil/easter.py b/python/dateutil/easter.py
new file mode 100644
index 0000000..e4def97
--- /dev/null
+++ b/python/dateutil/easter.py
@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+"""
+This module offers a generic easter computing method for any given year, using
+Western, Orthodox or Julian algorithms.
+"""
+
+import datetime
+
+__all__ = ["easter", "EASTER_JULIAN", "EASTER_ORTHODOX", "EASTER_WESTERN"]
+
+EASTER_JULIAN = 1
+EASTER_ORTHODOX = 2
+EASTER_WESTERN = 3
+
+
+def easter(year, method=EASTER_WESTERN):
+    """
+    This method was ported from the work done by GM Arts,
+    on top of the algorithm by Claus Tondering, which was
+    based in part on the algorithm of Ouding (1940), as
+    quoted in "Explanatory Supplement to the Astronomical
+    Almanac", P.  Kenneth Seidelmann, editor.
+
+    This algorithm implements three different easter
+    calculation methods:
+
+    1 - Original calculation in Julian calendar, valid in
+        dates after 326 AD
+    2 - Original method, with date converted to Gregorian
+        calendar, valid in years 1583 to 4099
+    3 - Revised method, in Gregorian calendar, valid in
+        years 1583 to 4099 as well
+
+    These methods are represented by the constants:
+
+    * ``EASTER_JULIAN   = 1``
+    * ``EASTER_ORTHODOX = 2``
+    * ``EASTER_WESTERN  = 3``
+
+    The default method is method 3.
+
+    More about the algorithm may be found at:
+
+    http://users.chariot.net.au/~gmarts/eastalg.htm
+
+    and
+
+    http://www.tondering.dk/claus/calendar.html
+
+    """
+
+    if not (1 <= method <= 3):
+        raise ValueError("invalid method")
+
+    # g - Golden year - 1
+    # c - Century
+    # h - (23 - Epact) mod 30
+    # i - Number of days from March 21 to Paschal Full Moon
+    # j - Weekday for PFM (0=Sunday, etc)
+    # p - Number of days from March 21 to Sunday on or before PFM
+    #     (-6 to 28 methods 1 & 3, to 56 for method 2)
+    # e - Extra days to add for method 2 (converting Julian
+    #     date to Gregorian date)
+
+    y = year
+    g = y % 19
+    e = 0
+    if method < 3:
+        # Old method
+        i = (19*g + 15) % 30
+        j = (y + y//4 + i) % 7
+        if method == 2:
+            # Extra dates to convert Julian to Gregorian date
+            e = 10
+            if y > 1600:
+                e = e + y//100 - 16 - (y//100 - 16)//4
+    else:
+        # New method
+        c = y//100
+        h = (c - c//4 - (8*c + 13)//25 + 19*g + 15) % 30
+        i = h - (h//28)*(1 - (h//28)*(29//(h + 1))*((21 - g)//11))
+        j = (y + y//4 + i + 2 - c + c//4) % 7
+
+    # p can be from -6 to 56 corresponding to dates 22 March to 23 May
+    # (later dates apply to method 2, although 23 May never actually occurs)
+    p = i - j + e
+    d = 1 + (p + 27 + (p + 6)//40) % 31
+    m = 3 + (p + 26)//30
+    return datetime.date(int(y), int(m), int(d))
diff --git a/python/dateutil/parser.py b/python/dateutil/parser.py
new file mode 100644
index 0000000..595331f
--- /dev/null
+++ b/python/dateutil/parser.py
@@ -0,0 +1,1374 @@
+# -*- coding: utf-8 -*-
+"""
+This module offers a generic date/time string parser which is able to parse
+most known formats to represent a date and/or time.
+
+This module attempts to be forgiving with regards to unlikely input formats,
+returning a datetime object even for dates which are ambiguous. If an element
+of a date/time stamp is omitted, the following rules are applied:
+- If AM or PM is left unspecified, a 24-hour clock is assumed, however, an hour
+  on a 12-hour clock (``0 <= hour <= 12``) *must* be specified if AM or PM is
+  specified.
+- If a time zone is omitted, a timezone-naive datetime is returned.
+
+If any other elements are missing, they are taken from the
+:class:`datetime.datetime` object passed to the parameter ``default``. If this
+results in a day number exceeding the valid number of days per month, the
+value falls back to the end of the month.
+
+Additional resources about date/time string formats can be found below:
+
+- `A summary of the international standard date and time notation
+  <http://www.cl.cam.ac.uk/~mgk25/iso-time.html>`_
+- `W3C Date and Time Formats <http://www.w3.org/TR/NOTE-datetime>`_
+- `Time Formats (Planetary Rings Node) <http://pds-rings.seti.org/tools/time_formats.html>`_
+- `CPAN ParseDate module
+  <http://search.cpan.org/~muir/Time-modules-2013.0912/lib/Time/ParseDate.pm>`_
+- `Java SimpleDateFormat Class
+  <https://docs.oracle.com/javase/6/docs/api/java/text/SimpleDateFormat.html>`_
+"""
+from __future__ import unicode_literals
+
+import datetime
+import string
+import time
+import collections
+import re
+from io import StringIO
+from calendar import monthrange
+
+from six import text_type, binary_type, integer_types
+
+from . import relativedelta
+from . import tz
+
+__all__ = ["parse", "parserinfo"]
+
+
+class _timelex(object):
+    # Fractional seconds are sometimes split by a comma
+    _split_decimal = re.compile("([.,])")
+
+    def __init__(self, instream):
+        if isinstance(instream, binary_type):
+            instream = instream.decode()
+
+        if isinstance(instream, text_type):
+            instream = StringIO(instream)
+
+        if getattr(instream, 'read', None) is None:
+            raise TypeError('Parser must be a string or character stream, not '
+                            '{itype}'.format(itype=instream.__class__.__name__))
+
+        self.instream = instream
+        self.charstack = []
+        self.tokenstack = []
+        self.eof = False
+
+    def get_token(self):
+        """
+        This function breaks the time string into lexical units (tokens), which
+        can be parsed by the parser. Lexical units are demarcated by changes in
+        the character set, so any continuous string of letters is considered
+        one unit, any continuous string of numbers is considered one unit.
+
+        The main complication arises from the fact that dots ('.') can be used
+        both as separators (e.g. "Sep.20.2009") or decimal points (e.g.
+        "4:30:21.447"). As such, it is necessary to read the full context of
+        any dot-separated strings before breaking it into tokens; as such, this
+        function maintains a "token stack", for when the ambiguous context
+        demands that multiple tokens be parsed at once.
+        """
+        if self.tokenstack:
+            return self.tokenstack.pop(0)
+
+        seenletters = False
+        token = None
+        state = None
+
+        while not self.eof:
+            # We only realize that we've reached the end of a token when we
+            # find a character that's not part of the current token - since
+            # that character may be part of the next token, it's stored in the
+            # charstack.
+            if self.charstack:
+                nextchar = self.charstack.pop(0)
+            else:
+                nextchar = self.instream.read(1)
+                while nextchar == '\x00':
+                    nextchar = self.instream.read(1)
+
+            if not nextchar:
+                self.eof = True
+                break
+            elif not state:
+                # First character of the token - determines if we're starting
+                # to parse a word, a number or something else.
+                token = nextchar
+                if self.isword(nextchar):
+                    state = 'a'
+                elif self.isnum(nextchar):
+                    state = '0'
+                elif self.isspace(nextchar):
+                    token = ' '
+                    break  # emit token
+                else:
+                    break  # emit token
+            elif state == 'a':
+                # If we've already started reading a word, we keep reading
+                # letters until we find something that's not part of a word.
+                seenletters = True
+                if self.isword(nextchar):
+                    token += nextchar
+                elif nextchar == '.':
+                    token += nextchar
+                    state = 'a.'
+                else:
+                    self.charstack.append(nextchar)
+                    break  # emit token
+            elif state == '0':
+                # If we've already started reading a number, we keep reading
+                # numbers until we find something that doesn't fit.
+                if self.isnum(nextchar):
+                    token += nextchar
+                elif nextchar == '.' or (nextchar == ',' and len(token) >= 2):
+                    token += nextchar
+                    state = '0.'
+                else:
+                    self.charstack.append(nextchar)
+                    break  # emit token
+            elif state == 'a.':
+                # If we've seen some letters and a dot separator, continue
+                # parsing, and the tokens will be broken up later.
+                seenletters = True
+                if nextchar == '.' or self.isword(nextchar):
+                    token += nextchar
+                elif self.isnum(nextchar) and token[-1] == '.':
+                    token += nextchar
+                    state = '0.'
+                else:
+                    self.charstack.append(nextchar)
+                    break  # emit token
+            elif state == '0.':
+                # If we've seen at least one dot separator, keep going, we'll
+                # break up the tokens later.
+                if nextchar == '.' or self.isnum(nextchar):
+                    token += nextchar
+                elif self.isword(nextchar) and token[-1] == '.':
+                    token += nextchar
+                    state = 'a.'
+                else:
+                    self.charstack.append(nextchar)
+                    break  # emit token
+
+        if (state in ('a.', '0.') and (seenletters or token.count('.') > 1 or
+                                       token[-1] in '.,')):
+            l = self._split_decimal.split(token)
+            token = l[0]
+            for tok in l[1:]:
+                if tok:
+                    self.tokenstack.append(tok)
+
+        if state == '0.' and token.count('.') == 0:
+            token = token.replace(',', '.')
+
+        return token
+
+    def __iter__(self):
+        return self
+
+    def __next__(self):
+        token = self.get_token()
+        if token is None:
+            raise StopIteration
+
+        return token
+
+    def next(self):
+        return self.__next__()  # Python 2.x support
+
+    @classmethod
+    def split(cls, s):
+        return list(cls(s))
+
+    @classmethod
+    def isword(cls, nextchar):
+        """ Whether or not the next character is part of a word """
+        return nextchar.isalpha()
+
+    @classmethod
+    def isnum(cls, nextchar):
+        """ Whether the next character is part of a number """
+        return nextchar.isdigit()
+
+    @classmethod
+    def isspace(cls, nextchar):
+        """ Whether the next character is whitespace """
+        return nextchar.isspace()
+
+
+class _resultbase(object):
+
+    def __init__(self):
+        for attr in self.__slots__:
+            setattr(self, attr, None)
+
+    def _repr(self, classname):
+        l = []
+        for attr in self.__slots__:
+            value = getattr(self, attr)
+            if value is not None:
+                l.append("%s=%s" % (attr, repr(value)))
+        return "%s(%s)" % (classname, ", ".join(l))
+
+    def __len__(self):
+        return (sum(getattr(self, attr) is not None
+                    for attr in self.__slots__))
+
+    def __repr__(self):
+        return self._repr(self.__class__.__name__)
+
+
+class parserinfo(object):
+    """
+    Class which handles what inputs are accepted. Subclass this to customize
+    the language and acceptable values for each parameter.
+
+    :param dayfirst:
+            Whether to interpret the first value in an ambiguous 3-integer date
+            (e.g. 01/05/09) as the day (``True``) or month (``False``). If
+            ``yearfirst`` is set to ``True``, this distinguishes between YDM
+            and YMD. Default is ``False``.
+
+    :param yearfirst:
+            Whether to interpret the first value in an ambiguous 3-integer date
+            (e.g. 01/05/09) as the year. If ``True``, the first number is taken
+            to be the year, otherwise the last number is taken to be the year.
+            Default is ``False``.
+    """
+
+    # m from a.m/p.m, t from ISO T separator
+    JUMP = [" ", ".", ",", ";", "-", "/", "'",
+            "at", "on", "and", "ad", "m", "t", "of",
+            "st", "nd", "rd", "th"]
+
+    WEEKDAYS = [("Mon", "Monday"),
+                ("Tue", "Tuesday"),
+                ("Wed", "Wednesday"),
+                ("Thu", "Thursday"),
+                ("Fri", "Friday"),
+                ("Sat", "Saturday"),
+                ("Sun", "Sunday")]
+    MONTHS = [("Jan", "January"),
+              ("Feb", "February"),
+              ("Mar", "March"),
+              ("Apr", "April"),
+              ("May", "May"),
+              ("Jun", "June"),
+              ("Jul", "July"),
+              ("Aug", "August"),
+              ("Sep", "Sept", "September"),
+              ("Oct", "October"),
+              ("Nov", "November"),
+              ("Dec", "December")]
+    HMS = [("h", "hour", "hours"),
+           ("m", "minute", "minutes"),
+           ("s", "second", "seconds")]
+    AMPM = [("am", "a"),
+            ("pm", "p")]
+    UTCZONE = ["UTC", "GMT", "Z"]
+    PERTAIN = ["of"]
+    TZOFFSET = {}
+
+    def __init__(self, dayfirst=False, yearfirst=False):
+        self._jump = self._convert(self.JUMP)
+        self._weekdays = self._convert(self.WEEKDAYS)
+        self._months = self._convert(self.MONTHS)
+        self._hms = self._convert(self.HMS)
+        self._ampm = self._convert(self.AMPM)
+        self._utczone = self._convert(self.UTCZONE)
+        self._pertain = self._convert(self.PERTAIN)
+
+        self.dayfirst = dayfirst
+        self.yearfirst = yearfirst
+
+        self._year = time.localtime().tm_year
+        self._century = self._year // 100 * 100
+
+    def _convert(self, lst):
+        dct = {}
+        for i, v in enumerate(lst):
+            if isinstance(v, tuple):
+                for v in v:
+                    dct[v.lower()] = i
+            else:
+                dct[v.lower()] = i
+        return dct
+
+    def jump(self, name):
+        return name.lower() in self._jump
+
+    def weekday(self, name):
+        if len(name) >= min(len(n) for n in self._weekdays.keys()):
+            try:
+                return self._weekdays[name.lower()]
+            except KeyError:
+                pass
+        return None
+
+    def month(self, name):
+        if len(name) >= min(len(n) for n in self._months.keys()):
+            try:
+                return self._months[name.lower()] + 1
+            except KeyError:
+                pass
+        return None
+
+    def hms(self, name):
+        try:
+            return self._hms[name.lower()]
+        except KeyError:
+            return None
+
+    def ampm(self, name):
+        try:
+            return self._ampm[name.lower()]
+        except KeyError:
+            return None
+
+    def pertain(self, name):
+        return name.lower() in self._pertain
+
+    def utczone(self, name):
+        return name.lower() in self._utczone
+
+    def tzoffset(self, name):
+        if name in self._utczone:
+            return 0
+
+        return self.TZOFFSET.get(name)
+
+    def convertyear(self, year, century_specified=False):
+        if year < 100 and not century_specified:
+            year += self._century
+            if abs(year - self._year) >= 50:
+                if year < self._year:
+                    year += 100
+                else:
+                    year -= 100
+        return year
+
+    def validate(self, res):
+        # move to info
+        if res.year is not None:
+            res.year = self.convertyear(res.year, res.century_specified)
+
+        if res.tzoffset == 0 and not res.tzname or res.tzname == 'Z':
+            res.tzname = "UTC"
+            res.tzoffset = 0
+        elif res.tzoffset != 0 and res.tzname and self.utczone(res.tzname):
+            res.tzoffset = 0
+        return True
+
+
+class _ymd(list):
+    def __init__(self, tzstr, *args, **kwargs):
+        super(self.__class__, self).__init__(*args, **kwargs)
+        self.century_specified = False
+        self.tzstr = tzstr
+
+    @staticmethod
+    def token_could_be_year(token, year):
+        try:
+            return int(token) == year
+        except ValueError:
+            return False
+
+    @staticmethod
+    def find_potential_year_tokens(year, tokens):
+        return [token for token in tokens if _ymd.token_could_be_year(token, year)]
+
+    def find_probable_year_index(self, tokens):
+        """
+        attempt to deduce if a pre 100 year was lost
+         due to padded zeros being taken off
+        """
+        for index, token in enumerate(self):
+            potential_year_tokens = _ymd.find_potential_year_tokens(token, tokens)
+            if len(potential_year_tokens) == 1 and len(potential_year_tokens[0]) > 2:
+                return index
+
+    def append(self, val):
+        if hasattr(val, '__len__'):
+            if val.isdigit() and len(val) > 2:
+                self.century_specified = True
+        elif val > 100:
+            self.century_specified = True
+
+        super(self.__class__, self).append(int(val))
+
+    def resolve_ymd(self, mstridx, yearfirst, dayfirst):
+        len_ymd = len(self)
+        year, month, day = (None, None, None)
+
+        if len_ymd > 3:
+            raise ValueError("More than three YMD values")
+        elif len_ymd == 1 or (mstridx != -1 and len_ymd == 2):
+            # One member, or two members with a month string
+            if mstridx != -1:
+                month = self[mstridx]
+                del self[mstridx]
+
+            if len_ymd > 1 or mstridx == -1:
+                if self[0] > 31:
+                    year = self[0]
+                else:
+                    day = self[0]
+
+        elif len_ymd == 2:
+            # Two members with numbers
+            if self[0] > 31:
+                # 99-01
+                year, month = self
+            elif self[1] > 31:
+                # 01-99
+                month, year = self
+            elif dayfirst and self[1] <= 12:
+                # 13-01
+                day, month = self
+            else:
+                # 01-13
+                month, day = self
+
+        elif len_ymd == 3:
+            # Three members
+            if mstridx == 0:
+                month, day, year = self
+            elif mstridx == 1:
+                if self[0] > 31 or (yearfirst and self[2] <= 31):
+                    # 99-Jan-01
+                    year, month, day = self
+                else:
+                    # 01-Jan-01
+                    # Give precendence to day-first, since
+                    # two-digit years is usually hand-written.
+                    day, month, year = self
+
+            elif mstridx == 2:
+                # WTF!?
+                if self[1] > 31:
+                    # 01-99-Jan
+                    day, year, month = self
+                else:
+                    # 99-01-Jan
+                    year, day, month = self
+
+            else:
+                if self[0] > 31 or \
+                    self.find_probable_year_index(_timelex.split(self.tzstr)) == 0 or \
+                   (yearfirst and self[1] <= 12 and self[2] <= 31):
+                    # 99-01-01
+                    if dayfirst and self[2] <= 12:
+                        year, day, month = self
+                    else:
+                        year, month, day = self
+                elif self[0] > 12 or (dayfirst and self[1] <= 12):
+                    # 13-01-01
+                    day, month, year = self
+                else:
+                    # 01-13-01
+                    month, day, year = self
+
+        return year, month, day
+
+
+class parser(object):
+    def __init__(self, info=None):
+        self.info = info or parserinfo()
+
+    def parse(self, timestr, default=None, ignoretz=False, tzinfos=None, **kwargs):
+        """
+        Parse the date/time string into a :class:`datetime.datetime` object.
+
+        :param timestr:
+            Any date/time string using the supported formats.
+
+        :param default:
+            The default datetime object, if this is a datetime object and not
+            ``None``, elements specified in ``timestr`` replace elements in the
+            default object.
+
+        :param ignoretz:
+            If set ``True``, time zones in parsed strings are ignored and a
+            naive :class:`datetime.datetime` object is returned.
+
+        :param tzinfos:
+            Additional time zone names / aliases which may be present in the
+            string. This argument maps time zone names (and optionally offsets
+            from those time zones) to time zones. This parameter can be a
+            dictionary with timezone aliases mapping time zone names to time
+            zones or a function taking two parameters (``tzname`` and
+            ``tzoffset``) and returning a time zone.
+
+            The timezones to which the names are mapped can be an integer
+            offset from UTC in minutes or a :class:`tzinfo` object.
+
+            .. doctest::
+               :options: +NORMALIZE_WHITESPACE
+
+                >>> from dateutil.parser import parse
+                >>> from dateutil.tz import gettz
+                >>> tzinfos = {"BRST": -10800, "CST": gettz("America/Chicago")}
+                >>> parse("2012-01-19 17:21:00 BRST", tzinfos=tzinfos)
+                datetime.datetime(2012, 1, 19, 17, 21, tzinfo=tzoffset(u'BRST', -10800))
+                >>> parse("2012-01-19 17:21:00 CST", tzinfos=tzinfos)
+                datetime.datetime(2012, 1, 19, 17, 21,
+                                  tzinfo=tzfile('/usr/share/zoneinfo/America/Chicago'))
+
+            This parameter is ignored if ``ignoretz`` is set.
+
+        :param **kwargs:
+            Keyword arguments as passed to ``_parse()``.
+
+        :return:
+            Returns a :class:`datetime.datetime` object or, if the
+            ``fuzzy_with_tokens`` option is ``True``, returns a tuple, the
+            first element being a :class:`datetime.datetime` object, the second
+            a tuple containing the fuzzy tokens.
+
+        :raises ValueError:
+            Raised for invalid or unknown string format, if the provided
+            :class:`tzinfo` is not in a valid format, or if an invalid date
+            would be created.
+
+        :raises TypeError:
+            Raised for non-string or character stream input.
+
+        :raises OverflowError:
+            Raised if the parsed date exceeds the largest valid C integer on
+            your system.
+        """
+
+        if default is None:
+            default = datetime.datetime.now().replace(hour=0, minute=0,
+                                                      second=0, microsecond=0)
+
+        res, skipped_tokens = self._parse(timestr, **kwargs)
+
+        if res is None:
+            raise ValueError("Unknown string format")
+
+        if len(res) == 0:
+            raise ValueError("String does not contain a date.")
+
+        repl = {}
+        for attr in ("year", "month", "day", "hour",
+                     "minute", "second", "microsecond"):
+            value = getattr(res, attr)
+            if value is not None:
+                repl[attr] = value
+
+        if 'day' not in repl:
+            # If the default day exceeds the last day of the month, fall back to
+            # the end of the month.
+            cyear = default.year if res.year is None else res.year
+            cmonth = default.month if res.month is None else res.month
+            cday = default.day if res.day is None else res.day
+
+            if cday > monthrange(cyear, cmonth)[1]:
+                repl['day'] = monthrange(cyear, cmonth)[1]
+
+        ret = default.replace(**repl)
+
+        if res.weekday is not None and not res.day:
+            ret = ret+relativedelta.relativedelta(weekday=res.weekday)
+
+        if not ignoretz:
+            if (isinstance(tzinfos, collections.Callable) or
+                    tzinfos and res.tzname in tzinfos):
+
+                if isinstance(tzinfos, collections.Callable):
+                    tzdata = tzinfos(res.tzname, res.tzoffset)
+                else:
+                    tzdata = tzinfos.get(res.tzname)
+
+                if isinstance(tzdata, datetime.tzinfo):
+                    tzinfo = tzdata
+                elif isinstance(tzdata, text_type):
+                    tzinfo = tz.tzstr(tzdata)
+                elif isinstance(tzdata, integer_types):
+                    tzinfo = tz.tzoffset(res.tzname, tzdata)
+                else:
+                    raise ValueError("Offset must be tzinfo subclass, "
+                                     "tz string, or int offset.")
+                ret = ret.replace(tzinfo=tzinfo)
+            elif res.tzname and res.tzname in time.tzname:
+                ret = ret.replace(tzinfo=tz.tzlocal())
+            elif res.tzoffset == 0:
+                ret = ret.replace(tzinfo=tz.tzutc())
+            elif res.tzoffset:
+                ret = ret.replace(tzinfo=tz.tzoffset(res.tzname, res.tzoffset))
+
+        if kwargs.get('fuzzy_with_tokens', False):
+            return ret, skipped_tokens
+        else:
+            return ret
+
+    class _result(_resultbase):
+        __slots__ = ["year", "month", "day", "weekday",
+                     "hour", "minute", "second", "microsecond",
+                     "tzname", "tzoffset", "ampm"]
+
+    def _parse(self, timestr, dayfirst=None, yearfirst=None, fuzzy=False,
+               fuzzy_with_tokens=False):
+        """
+        Private method which performs the heavy lifting of parsing, called from
+        ``parse()``, which passes on its ``kwargs`` to this function.
+
+        :param timestr:
+            The string to parse.
+
+        :param dayfirst:
+            Whether to interpret the first value in an ambiguous 3-integer date
+            (e.g. 01/05/09) as the day (``True``) or month (``False``). If
+            ``yearfirst`` is set to ``True``, this distinguishes between YDM
+            and YMD. If set to ``None``, this value is retrieved from the
+            current :class:`parserinfo` object (which itself defaults to
+            ``False``).
+
+        :param yearfirst:
+            Whether to interpret the first value in an ambiguous 3-integer date
+            (e.g. 01/05/09) as the year. If ``True``, the first number is taken
+            to be the year, otherwise the last number is taken to be the year.
+            If this is set to ``None``, the value is retrieved from the current
+            :class:`parserinfo` object (which itself defaults to ``False``).
+
+        :param fuzzy:
+            Whether to allow fuzzy parsing, allowing for string like "Today is
+            January 1, 2047 at 8:21:00AM".
+
+        :param fuzzy_with_tokens:
+            If ``True``, ``fuzzy`` is automatically set to True, and the parser
+            will return a tuple where the first element is the parsed
+            :class:`datetime.datetime` datetimestamp and the second element is
+            a tuple containing the portions of the string which were ignored:
+
+            .. doctest::
+
+                >>> from dateutil.parser import parse
+                >>> parse("Today is January 1, 2047 at 8:21:00AM", fuzzy_with_tokens=True)
+                (datetime.datetime(2047, 1, 1, 8, 21), (u'Today is ', u' ', u'at '))
+
+        """
+        if fuzzy_with_tokens:
+            fuzzy = True
+
+        info = self.info
+
+        if dayfirst is None:
+            dayfirst = info.dayfirst
+
+        if yearfirst is None:
+            yearfirst = info.yearfirst
+
+        res = self._result()
+        l = _timelex.split(timestr)         # Splits the timestr into tokens
+
+        # keep up with the last token skipped so we can recombine
+        # consecutively skipped tokens (-2 for when i begins at 0).
+        last_skipped_token_i = -2
+        skipped_tokens = list()
+
+        try:
+            # year/month/day list
+            ymd = _ymd(timestr)
+
+            # Index of the month string in ymd
+            mstridx = -1
+
+            len_l = len(l)
+            i = 0
+            while i < len_l:
+
+                # Check if it's a number
+                try:
+                    value_repr = l[i]
+                    value = float(value_repr)
+                except ValueError:
+                    value = None
+
+                if value is not None:
+                    # Token is a number
+                    len_li = len(l[i])
+                    i += 1
+
+                    if (len(ymd) == 3 and len_li in (2, 4)
+                        and res.hour is None and (i >= len_l or (l[i] != ':' and
+                                                  info.hms(l[i]) is None))):
+                        # 19990101T23[59]
+                        s = l[i-1]
+                        res.hour = int(s[:2])
+
+                        if len_li == 4:
+                            res.minute = int(s[2:])
+
+                    elif len_li == 6 or (len_li > 6 and l[i-1].find('.') == 6):
+                        # YYMMDD or HHMMSS[.ss]
+                        s = l[i-1]
+
+                        if not ymd and l[i-1].find('.') == -1:
+                            #ymd.append(info.convertyear(int(s[:2])))
+
+                            ymd.append(s[:2])
+                            ymd.append(s[2:4])
+                            ymd.append(s[4:])
+                        else:
+                            # 19990101T235959[.59]
+                            res.hour = int(s[:2])
+                            res.minute = int(s[2:4])
+                            res.second, res.microsecond = _parsems(s[4:])
+
+                    elif len_li in (8, 12, 14):
+                        # YYYYMMDD
+                        s = l[i-1]
+                        ymd.append(s[:4])
+                        ymd.append(s[4:6])
+                        ymd.append(s[6:8])
+
+                        if len_li > 8:
+                            res.hour = int(s[8:10])
+                            res.minute = int(s[10:12])
+
+                            if len_li > 12:
+                                res.second = int(s[12:])
+
+                    elif ((i < len_l and info.hms(l[i]) is not None) or
+                          (i+1 < len_l and l[i] == ' ' and
+                           info.hms(l[i+1]) is not None)):
+
+                        # HH[ ]h or MM[ ]m or SS[.ss][ ]s
+                        if l[i] == ' ':
+                            i += 1
+
+                        idx = info.hms(l[i])
+
+                        while True:
+                            if idx == 0:
+                                res.hour = int(value)
+
+                                if value % 1:
+                                    res.minute = int(60*(value % 1))
+
+                            elif idx == 1:
+                                res.minute = int(value)
+
+                                if value % 1:
+                                    res.second = int(60*(value % 1))
+
+                            elif idx == 2:
+                                res.second, res.microsecond = \
+                                    _parsems(value_repr)
+
+                            i += 1
+
+                            if i >= len_l or idx == 2:
+                                break
+
+                            # 12h00
+                            try:
+                                value_repr = l[i]
+                                value = float(value_repr)
+                            except ValueError:
+                                break
+                            else:
+                                i += 1
+                                idx += 1
+
+                                if i < len_l:
+                                    newidx = info.hms(l[i])
+
+                                    if newidx is not None:
+                                        idx = newidx
+
+                    elif (i == len_l and l[i-2] == ' ' and
+                          info.hms(l[i-3]) is not None):
+                        # X h MM or X m SS
+                        idx = info.hms(l[i-3])
+
+                        if idx == 0:               # h
+                            res.minute = int(value)
+
+                            sec_remainder = value % 1
+                            if sec_remainder:
+                                res.second = int(60 * sec_remainder)
+                        elif idx == 1:             # m
+                            res.second, res.microsecond = \
+                                _parsems(value_repr)
+
+                        # We don't need to advance the tokens here because the
+                        # i == len_l call indicates that we're looking at all
+                        # the tokens already.
+
+                    elif i+1 < len_l and l[i] == ':':
+                        # HH:MM[:SS[.ss]]
+                        res.hour = int(value)
+                        i += 1
+                        value = float(l[i])
+                        res.minute = int(value)
+
+                        if value % 1:
+                            res.second = int(60*(value % 1))
+
+                        i += 1
+
+                        if i < len_l and l[i] == ':':
+                            res.second, res.microsecond = _parsems(l[i+1])
+                            i += 2
+
+                    elif i < len_l and l[i] in ('-', '/', '.'):
+                        sep = l[i]
+                        ymd.append(value_repr)
+                        i += 1
+
+                        if i < len_l and not info.jump(l[i]):
+                            try:
+                                # 01-01[-01]
+                                ymd.append(l[i])
+                            except ValueError:
+                                # 01-Jan[-01]
+                                value = info.month(l[i])
+
+                                if value is not None:
+                                    ymd.append(value)
+                                    assert mstridx == -1
+                                    mstridx = len(ymd)-1
+                                else:
+                                    return None, None
+
+                            i += 1
+
+                            if i < len_l and l[i] == sep:
+                                # We have three members
+                                i += 1
+                                value = info.month(l[i])
+
+                                if value is not None:
+                                    ymd.append(value)
+                                    mstridx = len(ymd)-1
+                                    assert mstridx == -1
+                                else:
+                                    ymd.append(l[i])
+
+                                i += 1
+                    elif i >= len_l or info.jump(l[i]):
+                        if i+1 < len_l and info.ampm(l[i+1]) is not None:
+                            # 12 am
+                            res.hour = int(value)
+
+                            if res.hour < 12 and info.ampm(l[i+1]) == 1:
+                                res.hour += 12
+                            elif res.hour == 12 and info.ampm(l[i+1]) == 0:
+                                res.hour = 0
+
+                            i += 1
+                        else:
+                            # Year, month or day
+                            ymd.append(value)
+                        i += 1
+                    elif info.ampm(l[i]) is not None:
+
+                        # 12am
+                        res.hour = int(value)
+
+                        if res.hour < 12 and info.ampm(l[i]) == 1:
+                            res.hour += 12
+                        elif res.hour == 12 and info.ampm(l[i]) == 0:
+                            res.hour = 0
+                        i += 1
+
+                    elif not fuzzy:
+                        return None, None
+                    else:
+                        i += 1
+                    continue
+
+                # Check weekday
+                value = info.weekday(l[i])
+                if value is not None:
+                    res.weekday = value
+                    i += 1
+                    continue
+
+                # Check month name
+                value = info.month(l[i])
+                if value is not None:
+                    ymd.append(value)
+                    assert mstridx == -1
+                    mstridx = len(ymd)-1
+
+                    i += 1
+                    if i < len_l:
+                        if l[i] in ('-', '/'):
+                            # Jan-01[-99]
+                            sep = l[i]
+                            i += 1
+                            ymd.append(l[i])
+                            i += 1
+
+                            if i < len_l and l[i] == sep:
+                                # Jan-01-99
+                                i += 1
+                                ymd.append(l[i])
+                                i += 1
+
+                        elif (i+3 < len_l and l[i] == l[i+2] == ' '
+                              and info.pertain(l[i+1])):
+                            # Jan of 01
+                            # In this case, 01 is clearly year
+                            try:
+                                value = int(l[i+3])
+                            except ValueError:
+                                # Wrong guess
+                                pass
+                            else:
+                                # Convert it here to become unambiguous
+                                ymd.append(str(info.convertyear(value)))
+                            i += 4
+                    continue
+
+                # Check am/pm
+                value = info.ampm(l[i])
+                if value is not None:
+                    # For fuzzy parsing, 'a' or 'am' (both valid English words)
+                    # may erroneously trigger the AM/PM flag. Deal with that
+                    # here.
+                    val_is_ampm = True
+
+                    # If there's already an AM/PM flag, this one isn't one.
+                    if fuzzy and res.ampm is not None:
+                        val_is_ampm = False
+
+                    # If AM/PM is found and hour is not, raise a ValueError
+                    if res.hour is None:
+                        if fuzzy:
+                            val_is_ampm = False
+                        else:
+                            raise ValueError('No hour specified with ' +
+                                             'AM or PM flag.')
+                    elif not 0 <= res.hour <= 12:
+                        # If AM/PM is found, it's a 12 hour clock, so raise
+                        # an error for invalid range
+                        if fuzzy:
+                            val_is_ampm = False
+                        else:
+                            raise ValueError('Invalid hour specified for ' +
+                                             '12-hour clock.')
+
+                    if val_is_ampm:
+                        if value == 1 and res.hour < 12:
+                            res.hour += 12
+                        elif value == 0 and res.hour == 12:
+                            res.hour = 0
+
+                        res.ampm = value
+
+                    elif fuzzy:
+                        last_skipped_token_i = self._skip_token(skipped_tokens,
+                                                    last_skipped_token_i, i, l)
+                    i += 1
+                    continue
+
+                # Check for a timezone name
+                if (res.hour is not None and len(l[i]) <= 5 and
+                        res.tzname is None and res.tzoffset is None and
+                        not [x for x in l[i] if x not in
+                             string.ascii_uppercase]):
+                    res.tzname = l[i]
+                    res.tzoffset = info.tzoffset(res.tzname)
+                    i += 1
+
+                    # Check for something like GMT+3, or BRST+3. Notice
+                    # that it doesn't mean "I am 3 hours after GMT", but
+                    # "my time +3 is GMT". If found, we reverse the
+                    # logic so that timezone parsing code will get it
+                    # right.
+                    if i < len_l and l[i] in ('+', '-'):
+                        l[i] = ('+', '-')[l[i] == '+']
+                        res.tzoffset = None
+                        if info.utczone(res.tzname):
+                            # With something like GMT+3, the timezone
+                            # is *not* GMT.
+                            res.tzname = None
+
+                    continue
+
+                # Check for a numbered timezone
+                if res.hour is not None and l[i] in ('+', '-'):
+                    signal = (-1, 1)[l[i] == '+']
+                    i += 1
+                    len_li = len(l[i])
+
+                    if len_li == 4:
+                        # -0300
+                        res.tzoffset = int(l[i][:2])*3600+int(l[i][2:])*60
+                    elif i+1 < len_l and l[i+1] == ':':
+                        # -03:00
+                        res.tzoffset = int(l[i])*3600+int(l[i+2])*60
+                        i += 2
+                    elif len_li <= 2:
+                        # -[0]3
+                        res.tzoffset = int(l[i][:2])*3600
+                    else:
+                        return None, None
+                    i += 1
+
+                    res.tzoffset *= signal
+
+                    # Look for a timezone name between parenthesis
+                    if (i+3 < len_l and
+                        info.jump(l[i]) and l[i+1] == '(' and l[i+3] == ')' and
+                        3 <= len(l[i+2]) <= 5 and
+                        not [x for x in l[i+2]
+                             if x not in string.ascii_uppercase]):
+                        # -0300 (BRST)
+                        res.tzname = l[i+2]
+                        i += 4
+                    continue
+
+                # Check jumps
+                if not (info.jump(l[i]) or fuzzy):
+                    return None, None
+
+                last_skipped_token_i = self._skip_token(skipped_tokens,
+                                                last_skipped_token_i, i, l)
+                i += 1
+
+            # Process year/month/day
+            year, month, day = ymd.resolve_ymd(mstridx, yearfirst, dayfirst)
+            if year is not None:
+                res.year = year
+                res.century_specified = ymd.century_specified
+
+            if month is not None:
+                res.month = month
+
+            if day is not None:
+                res.day = day
+
+        except (IndexError, ValueError, AssertionError):
+            return None, None
+
+        if not info.validate(res):
+            return None, None
+
+        if fuzzy_with_tokens:
+            return res, tuple(skipped_tokens)
+        else:
+            return res, None
+
+    @staticmethod
+    def _skip_token(skipped_tokens, last_skipped_token_i, i, l):
+        if last_skipped_token_i == i - 1:
+            # recombine the tokens
+            skipped_tokens[-1] += l[i]
+        else:
+            # just append
+            skipped_tokens.append(l[i])
+        last_skipped_token_i = i
+        return last_skipped_token_i
+
+
+DEFAULTPARSER = parser()
+
+
+def parse(timestr, parserinfo=None, **kwargs):
+    """
+
+    Parse a string in one of the supported formats, using the
+    ``parserinfo`` parameters.
+
+    :param timestr:
+        A string containing a date/time stamp.
+
+    :param parserinfo:
+        A :class:`parserinfo` object containing parameters for the parser.
+        If ``None``, the default arguments to the :class:`parserinfo`
+        constructor are used.
+
+    The ``**kwargs`` parameter takes the following keyword arguments:
+
+    :param default:
+        The default datetime object, if this is a datetime object and not
+        ``None``, elements specified in ``timestr`` replace elements in the
+        default object.
+
+    :param ignoretz:
+        If set ``True``, time zones in parsed strings are ignored and a naive
+        :class:`datetime` object is returned.
+
+    :param tzinfos:
+            Additional time zone names / aliases which may be present in the
+            string. This argument maps time zone names (and optionally offsets
+            from those time zones) to time zones. This parameter can be a
+            dictionary with timezone aliases mapping time zone names to time
+            zones or a function taking two parameters (``tzname`` and
+            ``tzoffset``) and returning a time zone.
+
+            The timezones to which the names are mapped can be an integer
+            offset from UTC in minutes or a :class:`tzinfo` object.
+
+            .. doctest::
+               :options: +NORMALIZE_WHITESPACE
+
+                >>> from dateutil.parser import parse
+                >>> from dateutil.tz import gettz
+                >>> tzinfos = {"BRST": -10800, "CST": gettz("America/Chicago")}
+                >>> parse("2012-01-19 17:21:00 BRST", tzinfos=tzinfos)
+                datetime.datetime(2012, 1, 19, 17, 21, tzinfo=tzoffset(u'BRST', -10800))
+                >>> parse("2012-01-19 17:21:00 CST", tzinfos=tzinfos)
+                datetime.datetime(2012, 1, 19, 17, 21,
+                                  tzinfo=tzfile('/usr/share/zoneinfo/America/Chicago'))
+
+            This parameter is ignored if ``ignoretz`` is set.
+
+    :param dayfirst:
+        Whether to interpret the first value in an ambiguous 3-integer date
+        (e.g. 01/05/09) as the day (``True``) or month (``False``). If
+        ``yearfirst`` is set to ``True``, this distinguishes between YDM and
+        YMD. If set to ``None``, this value is retrieved from the current
+        :class:`parserinfo` object (which itself defaults to ``False``).
+
+    :param yearfirst:
+        Whether to interpret the first value in an ambiguous 3-integer date
+        (e.g. 01/05/09) as the year. If ``True``, the first number is taken to
+        be the year, otherwise the last number is taken to be the year. If
+        this is set to ``None``, the value is retrieved from the current
+        :class:`parserinfo` object (which itself defaults to ``False``).
+
+    :param fuzzy:
+        Whether to allow fuzzy parsing, allowing for string like "Today is
+        January 1, 2047 at 8:21:00AM".
+
+    :param fuzzy_with_tokens:
+        If ``True``, ``fuzzy`` is automatically set to True, and the parser
+        will return a tuple where the first element is the parsed
+        :class:`datetime.datetime` datetimestamp and the second element is
+        a tuple containing the portions of the string which were ignored:
+
+        .. doctest::
+
+            >>> from dateutil.parser import parse
+            >>> parse("Today is January 1, 2047 at 8:21:00AM", fuzzy_with_tokens=True)
+            (datetime.datetime(2047, 1, 1, 8, 21), (u'Today is ', u' ', u'at '))
+
+    :return:
+        Returns a :class:`datetime.datetime` object or, if the
+        ``fuzzy_with_tokens`` option is ``True``, returns a tuple, the
+        first element being a :class:`datetime.datetime` object, the second
+        a tuple containing the fuzzy tokens.
+
+    :raises ValueError:
+        Raised for invalid or unknown string format, if the provided
+        :class:`tzinfo` is not in a valid format, or if an invalid date
+        would be created.
+
+    :raises OverflowError:
+        Raised if the parsed date exceeds the largest valid C integer on
+        your system.
+    """
+    if parserinfo:
+        return parser(parserinfo).parse(timestr, **kwargs)
+    else:
+        return DEFAULTPARSER.parse(timestr, **kwargs)
+
+
+class _tzparser(object):
+
+    class _result(_resultbase):
+
+        __slots__ = ["stdabbr", "stdoffset", "dstabbr", "dstoffset",
+                     "start", "end"]
+
+        class _attr(_resultbase):
+            __slots__ = ["month", "week", "weekday",
+                         "yday", "jyday", "day", "time"]
+
+        def __repr__(self):
+            return self._repr("")
+
+        def __init__(self):
+            _resultbase.__init__(self)
+            self.start = self._attr()
+            self.end = self._attr()
+
+    def parse(self, tzstr):
+        res = self._result()
+        l = _timelex.split(tzstr)
+        try:
+
+            len_l = len(l)
+
+            i = 0
+            while i < len_l:
+                # BRST+3[BRDT[+2]]
+                j = i
+                while j < len_l and not [x for x in l[j]
+                                         if x in "0123456789:,-+"]:
+                    j += 1
+                if j != i:
+                    if not res.stdabbr:
+                        offattr = "stdoffset"
+                        res.stdabbr = "".join(l[i:j])
+                    else:
+                        offattr = "dstoffset"
+                        res.dstabbr = "".join(l[i:j])
+                    i = j
+                    if (i < len_l and (l[i] in ('+', '-') or l[i][0] in
+                                       "0123456789")):
+                        if l[i] in ('+', '-'):
+                            # Yes, that's right.  See the TZ variable
+                            # documentation.
+                            signal = (1, -1)[l[i] == '+']
+                            i += 1
+                        else:
+                            signal = -1
+                        len_li = len(l[i])
+                        if len_li == 4:
+                            # -0300
+                            setattr(res, offattr, (int(l[i][:2])*3600 +
+                                                   int(l[i][2:])*60)*signal)
+                        elif i+1 < len_l and l[i+1] == ':':
+                            # -03:00
+                            setattr(res, offattr,
+                                    (int(l[i])*3600+int(l[i+2])*60)*signal)
+                            i += 2
+                        elif len_li <= 2:
+                            # -[0]3
+                            setattr(res, offattr,
+                                    int(l[i][:2])*3600*signal)
+                        else:
+                            return None
+                        i += 1
+                    if res.dstabbr:
+                        break
+                else:
+                    break
+
+            if i < len_l:
+                for j in range(i, len_l):
+                    if l[j] == ';':
+                        l[j] = ','
+
+                assert l[i] == ','
+
+                i += 1
+
+            if i >= len_l:
+                pass
+            elif (8 <= l.count(',') <= 9 and
+                  not [y for x in l[i:] if x != ','
+                       for y in x if y not in "0123456789"]):
+                # GMT0BST,3,0,30,3600,10,0,26,7200[,3600]
+                for x in (res.start, res.end):
+                    x.month = int(l[i])
+                    i += 2
+                    if l[i] == '-':
+                        value = int(l[i+1])*-1
+                        i += 1
+                    else:
+                        value = int(l[i])
+                    i += 2
+                    if value:
+                        x.week = value
+                        x.weekday = (int(l[i])-1) % 7
+                    else:
+                        x.day = int(l[i])
+                    i += 2
+                    x.time = int(l[i])
+                    i += 2
+                if i < len_l:
+                    if l[i] in ('-', '+'):
+                        signal = (-1, 1)[l[i] == "+"]
+                        i += 1
+                    else:
+                        signal = 1
+                    res.dstoffset = (res.stdoffset+int(l[i]))*signal
+            elif (l.count(',') == 2 and l[i:].count('/') <= 2 and
+                  not [y for x in l[i:] if x not in (',', '/', 'J', 'M',
+                                                     '.', '-', ':')
+                       for y in x if y not in "0123456789"]):
+                for x in (res.start, res.end):
+                    if l[i] == 'J':
+                        # non-leap year day (1 based)
+                        i += 1
+                        x.jyday = int(l[i])
+                    elif l[i] == 'M':
+                        # month[-.]week[-.]weekday
+                        i += 1
+                        x.month = int(l[i])
+                        i += 1
+                        assert l[i] in ('-', '.')
+                        i += 1
+                        x.week = int(l[i])
+                        if x.week == 5:
+                            x.week = -1
+                        i += 1
+                        assert l[i] in ('-', '.')
+                        i += 1
+                        x.weekday = (int(l[i])-1) % 7
+                    else:
+                        # year day (zero based)
+                        x.yday = int(l[i])+1
+
+                    i += 1
+
+                    if i < len_l and l[i] == '/':
+                        i += 1
+                        # start time
+                        len_li = len(l[i])
+                        if len_li == 4:
+                            # -0300
+                            x.time = (int(l[i][:2])*3600+int(l[i][2:])*60)
+                        elif i+1 < len_l and l[i+1] == ':':
+                            # -03:00
+                            x.time = int(l[i])*3600+int(l[i+2])*60
+                            i += 2
+                            if i+1 < len_l and l[i+1] == ':':
+                                i += 2
+                                x.time += int(l[i])
+                        elif len_li <= 2:
+                            # -[0]3
+                            x.time = (int(l[i][:2])*3600)
+                        else:
+                            return None
+                        i += 1
+
+                    assert i == len_l or l[i] == ','
+
+                    i += 1
+
+                assert i >= len_l
+
+        except (IndexError, ValueError, AssertionError):
+            return None
+
+        return res
+
+
+DEFAULTTZPARSER = _tzparser()
+
+
+def _parsetz(tzstr):
+    return DEFAULTTZPARSER.parse(tzstr)
+
+
+def _parsems(value):
+    """Parse a I[.F] seconds value into (seconds, microseconds)."""
+    if "." not in value:
+        return int(value), 0
+    else:
+        i, f = value.split(".")
+        return int(i), int(f.ljust(6, "0")[:6])
+
+
+# vim:ts=4:sw=4:et
diff --git a/python/dateutil/relativedelta.py b/python/dateutil/relativedelta.py
new file mode 100644
index 0000000..0e66afc
--- /dev/null
+++ b/python/dateutil/relativedelta.py
@@ -0,0 +1,549 @@
+# -*- coding: utf-8 -*-
+import datetime
+import calendar
+
+import operator
+from math import copysign
+
+from six import integer_types
+from warnings import warn
+
+from ._common import weekday
+
+MO, TU, WE, TH, FR, SA, SU = weekdays = tuple(weekday(x) for x in range(7))
+
+__all__ = ["relativedelta", "MO", "TU", "WE", "TH", "FR", "SA", "SU"]
+
+
+class relativedelta(object):
+    """
+    The relativedelta type is based on the specification of the excellent
+    work done by M.-A. Lemburg in his
+    `mx.DateTime <http://www.egenix.com/files/python/mxDateTime.html>`_ extension.
+    However, notice that this type does *NOT* implement the same algorithm as
+    his work. Do *NOT* expect it to behave like mx.DateTime's counterpart.
+
+    There are two different ways to build a relativedelta instance. The
+    first one is passing it two date/datetime classes::
+
+        relativedelta(datetime1, datetime2)
+
+    The second one is passing it any number of the following keyword arguments::
+
+        relativedelta(arg1=x,arg2=y,arg3=z...)
+
+        year, month, day, hour, minute, second, microsecond:
+            Absolute information (argument is singular); adding or subtracting a
+            relativedelta with absolute information does not perform an aritmetic
+            operation, but rather REPLACES the corresponding value in the
+            original datetime with the value(s) in relativedelta.
+
+        years, months, weeks, days, hours, minutes, seconds, microseconds:
+            Relative information, may be negative (argument is plural); adding
+            or subtracting a relativedelta with relative information performs
+            the corresponding aritmetic operation on the original datetime value
+            with the information in the relativedelta.
+
+        weekday:
+            One of the weekday instances (MO, TU, etc). These instances may
+            receive a parameter N, specifying the Nth weekday, which could
+            be positive or negative (like MO(+1) or MO(-2). Not specifying
+            it is the same as specifying +1. You can also use an integer,
+            where 0=MO.
+
+        leapdays:
+            Will add given days to the date found, if year is a leap
+            year, and the date found is post 28 of february.
+
+        yearday, nlyearday:
+            Set the yearday or the non-leap year day (jump leap days).
+            These are converted to day/month/leapdays information.
+
+    Here is the behavior of operations with relativedelta:
+
+    1. Calculate the absolute year, using the 'year' argument, or the
+       original datetime year, if the argument is not present.
+
+    2. Add the relative 'years' argument to the absolute year.
+
+    3. Do steps 1 and 2 for month/months.
+
+    4. Calculate the absolute day, using the 'day' argument, or the
+       original datetime day, if the argument is not present. Then,
+       subtract from the day until it fits in the year and month
+       found after their operations.
+
+    5. Add the relative 'days' argument to the absolute day. Notice
+       that the 'weeks' argument is multiplied by 7 and added to
+       'days'.
+
+    6. Do steps 1 and 2 for hour/hours, minute/minutes, second/seconds,
+       microsecond/microseconds.
+
+    7. If the 'weekday' argument is present, calculate the weekday,
+       with the given (wday, nth) tuple. wday is the index of the
+       weekday (0-6, 0=Mon), and nth is the number of weeks to add
+       forward or backward, depending on its signal. Notice that if
+       the calculated date is already Monday, for example, using
+       (0, 1) or (0, -1) won't change the day.
+    """
+
+    def __init__(self, dt1=None, dt2=None,
+                 years=0, months=0, days=0, leapdays=0, weeks=0,
+                 hours=0, minutes=0, seconds=0, microseconds=0,
+                 year=None, month=None, day=None, weekday=None,
+                 yearday=None, nlyearday=None,
+                 hour=None, minute=None, second=None, microsecond=None):
+
+        # Check for non-integer values in integer-only quantities
+        if any(x is not None and x != int(x) for x in (years, months)):
+            raise ValueError("Non-integer years and months are "
+                             "ambiguous and not currently supported.")
+
+        if dt1 and dt2:
+            # datetime is a subclass of date. So both must be date
+            if not (isinstance(dt1, datetime.date) and
+                    isinstance(dt2, datetime.date)):
+                raise TypeError("relativedelta only diffs datetime/date")
+
+            # We allow two dates, or two datetimes, so we coerce them to be
+            # of the same type
+            if (isinstance(dt1, datetime.datetime) !=
+                    isinstance(dt2, datetime.datetime)):
+                if not isinstance(dt1, datetime.datetime):
+                    dt1 = datetime.datetime.fromordinal(dt1.toordinal())
+                elif not isinstance(dt2, datetime.datetime):
+                    dt2 = datetime.datetime.fromordinal(dt2.toordinal())
+
+            self.years = 0
+            self.months = 0
+            self.days = 0
+            self.leapdays = 0
+            self.hours = 0
+            self.minutes = 0
+            self.seconds = 0
+            self.microseconds = 0
+            self.year = None
+            self.month = None
+            self.day = None
+            self.weekday = None
+            self.hour = None
+            self.minute = None
+            self.second = None
+            self.microsecond = None
+            self._has_time = 0
+
+            # Get year / month delta between the two
+            months = (dt1.year - dt2.year) * 12 + (dt1.month - dt2.month)
+            self._set_months(months)
+
+            # Remove the year/month delta so the timedelta is just well-defined
+            # time units (seconds, days and microseconds)
+            dtm = self.__radd__(dt2)
+
+            # If we've overshot our target, make an adjustment
+            if dt1 < dt2:
+                compare = operator.gt
+                increment = 1
+            else:
+                compare = operator.lt
+                increment = -1
+
+            while compare(dt1, dtm):
+                months += increment
+                self._set_months(months)
+                dtm = self.__radd__(dt2)
+
+            # Get the timedelta between the "months-adjusted" date and dt1
+            delta = dt1 - dtm
+            self.seconds = delta.seconds + delta.days * 86400
+            self.microseconds = delta.microseconds
+        else:
+            # Relative information
+            self.years = years
+            self.months = months
+            self.days = days + weeks * 7
+            self.leapdays = leapdays
+            self.hours = hours
+            self.minutes = minutes
+            self.seconds = seconds
+            self.microseconds = microseconds
+
+            # Absolute information
+            self.year = year
+            self.month = month
+            self.day = day
+            self.hour = hour
+            self.minute = minute
+            self.second = second
+            self.microsecond = microsecond
+
+            if any(x is not None and int(x) != x
+                   for x in (year, month, day, hour,
+                             minute, second, microsecond)):
+                # For now we'll deprecate floats - later it'll be an error.
+                warn("Non-integer value passed as absolute information. " +
+                     "This is not a well-defined condition and will raise " +
+                     "errors in future versions.", DeprecationWarning)
+
+            if isinstance(weekday, integer_types):
+                self.weekday = weekdays[weekday]
+            else:
+                self.weekday = weekday
+
+            yday = 0
+            if nlyearday:
+                yday = nlyearday
+            elif yearday:
+                yday = yearday
+                if yearday > 59:
+                    self.leapdays = -1
+            if yday:
+                ydayidx = [31, 59, 90, 120, 151, 181, 212,
+                           243, 273, 304, 334, 366]
+                for idx, ydays in enumerate(ydayidx):
+                    if yday <= ydays:
+                        self.month = idx+1
+                        if idx == 0:
+                            self.day = yday
+                        else:
+                            self.day = yday-ydayidx[idx-1]
+                        break
+                else:
+                    raise ValueError("invalid year day (%d)" % yday)
+
+        self._fix()
+
+    def _fix(self):
+        if abs(self.microseconds) > 999999:
+            s = _sign(self.microseconds)
+            div, mod = divmod(self.microseconds * s, 1000000)
+            self.microseconds = mod * s
+            self.seconds += div * s
+        if abs(self.seconds) > 59:
+            s = _sign(self.seconds)
+            div, mod = divmod(self.seconds * s, 60)
+            self.seconds = mod * s
+            self.minutes += div * s
+        if abs(self.minutes) > 59:
+            s = _sign(self.minutes)
+            div, mod = divmod(self.minutes * s, 60)
+            self.minutes = mod * s
+            self.hours += div * s
+        if abs(self.hours) > 23:
+            s = _sign(self.hours)
+            div, mod = divmod(self.hours * s, 24)
+            self.hours = mod * s
+            self.days += div * s
+        if abs(self.months) > 11:
+            s = _sign(self.months)
+            div, mod = divmod(self.months * s, 12)
+            self.months = mod * s
+            self.years += div * s
+        if (self.hours or self.minutes or self.seconds or self.microseconds
+                or self.hour is not None or self.minute is not None or
+                self.second is not None or self.microsecond is not None):
+            self._has_time = 1
+        else:
+            self._has_time = 0
+
+    @property
+    def weeks(self):
+        return self.days // 7
+
+    @weeks.setter
+    def weeks(self, value):
+        self.days = self.days - (self.weeks * 7) + value * 7
+
+    def _set_months(self, months):
+        self.months = months
+        if abs(self.months) > 11:
+            s = _sign(self.months)
+            div, mod = divmod(self.months * s, 12)
+            self.months = mod * s
+            self.years = div * s
+        else:
+            self.years = 0
+
+    def normalized(self):
+        """
+        Return a version of this object represented entirely using integer
+        values for the relative attributes.
+
+        >>> relativedelta(days=1.5, hours=2).normalized()
+        relativedelta(days=1, hours=14)
+
+        :return:
+            Returns a :class:`dateutil.relativedelta.relativedelta` object.
+        """
+        # Cascade remainders down (rounding each to roughly nearest microsecond)
+        days = int(self.days)
+
+        hours_f = round(self.hours + 24 * (self.days - days), 11)
+        hours = int(hours_f)
+
+        minutes_f = round(self.minutes + 60 * (hours_f - hours), 10)
+        minutes = int(minutes_f)
+
+        seconds_f = round(self.seconds + 60 * (minutes_f - minutes), 8)
+        seconds = int(seconds_f)
+
+        microseconds = round(self.microseconds + 1e6 * (seconds_f - seconds))
+
+        # Constructor carries overflow back up with call to _fix()
+        return self.__class__(years=self.years, months=self.months,
+                              days=days, hours=hours, minutes=minutes,
+                              seconds=seconds, microseconds=microseconds,
+                              leapdays=self.leapdays, year=self.year,
+                              month=self.month, day=self.day,
+                              weekday=self.weekday, hour=self.hour,
+                              minute=self.minute, second=self.second,
+                              microsecond=self.microsecond)
+
+    def __add__(self, other):
+        if isinstance(other, relativedelta):
+            return self.__class__(years=other.years + self.years,
+                                 months=other.months + self.months,
+                                 days=other.days + self.days,
+                                 hours=other.hours + self.hours,
+                                 minutes=other.minutes + self.minutes,
+                                 seconds=other.seconds + self.seconds,
+                                 microseconds=(other.microseconds +
+                                               self.microseconds),
+                                 leapdays=other.leapdays or self.leapdays,
+                                 year=(other.year if other.year is not None
+                                       else self.year),
+                                 month=(other.month if other.month is not None
+                                        else self.month),
+                                 day=(other.day if other.day is not None
+                                      else self.day),
+                                 weekday=(other.weekday if other.weekday is not None
+                                          else self.weekday),
+                                 hour=(other.hour if other.hour is not None
+                                       else self.hour),
+                                 minute=(other.minute if other.minute is not None
+                                         else self.minute),
+                                 second=(other.second if other.second is not None
+                                         else self.second),
+                                 microsecond=(other.microsecond if other.microsecond
+                                              is not None else
+                                              self.microsecond))
+        if isinstance(other, datetime.timedelta):
+            return self.__class__(years=self.years,
+                                  months=self.months,
+                                  days=self.days + other.days,
+                                  hours=self.hours,
+                                  minutes=self.minutes,
+                                  seconds=self.seconds + other.seconds,
+                                  microseconds=self.microseconds + other.microseconds,
+                                  leapdays=self.leapdays,
+                                  year=self.year,
+                                  month=self.month,
+                                  day=self.day,
+                                  weekday=self.weekday,
+                                  hour=self.hour,
+                                  minute=self.minute,
+                                  second=self.second,
+                                  microsecond=self.microsecond)
+        if not isinstance(other, datetime.date):
+            return NotImplemented
+        elif self._has_time and not isinstance(other, datetime.datetime):
+            other = datetime.datetime.fromordinal(other.toordinal())
+        year = (self.year or other.year)+self.years
+        month = self.month or other.month
+        if self.months:
+            assert 1 <= abs(self.months) <= 12
+            month += self.months
+            if month > 12:
+                year += 1
+                month -= 12
+            elif month < 1:
+                year -= 1
+                month += 12
+        day = min(calendar.monthrange(year, month)[1],
+                  self.day or other.day)
+        repl = {"year": year, "month": month, "day": day}
+        for attr in ["hour", "minute", "second", "microsecond"]:
+            value = getattr(self, attr)
+            if value is not None:
+                repl[attr] = value
+        days = self.days
+        if self.leapdays and month > 2 and calendar.isleap(year):
+            days += self.leapdays
+        ret = (other.replace(**repl)
+               + datetime.timedelta(days=days,
+                                    hours=self.hours,
+                                    minutes=self.minutes,
+                                    seconds=self.seconds,
+                                    microseconds=self.microseconds))
+        if self.weekday:
+            weekday, nth = self.weekday.weekday, self.weekday.n or 1
+            jumpdays = (abs(nth) - 1) * 7
+            if nth > 0:
+                jumpdays += (7 - ret.weekday() + weekday) % 7
+            else:
+                jumpdays += (ret.weekday() - weekday) % 7
+                jumpdays *= -1
+            ret += datetime.timedelta(days=jumpdays)
+        return ret
+
+    def __radd__(self, other):
+        return self.__add__(other)
+
+    def __rsub__(self, other):
+        return self.__neg__().__radd__(other)
+
+    def __sub__(self, other):
+        if not isinstance(other, relativedelta):
+            return NotImplemented   # In case the other object defines __rsub__
+        return self.__class__(years=self.years - other.years,
+                             months=self.months - other.months,
+                             days=self.days - other.days,
+                             hours=self.hours - other.hours,
+                             minutes=self.minutes - other.minutes,
+                             seconds=self.seconds - other.seconds,
+                             microseconds=self.microseconds - other.microseconds,
+                             leapdays=self.leapdays or other.leapdays,
+                             year=(self.year if self.year is not None
+                                   else other.year),
+                             month=(self.month if self.month is not None else
+                                    other.month),
+                             day=(self.day if self.day is not None else
+                                  other.day),
+                             weekday=(self.weekday if self.weekday is not None else
+                                      other.weekday),
+                             hour=(self.hour if self.hour is not None else
+                                   other.hour),
+                             minute=(self.minute if self.minute is not None else
+                                     other.minute),
+                             second=(self.second if self.second is not None else
+                                     other.second),
+                             microsecond=(self.microsecond if self.microsecond
+                                          is not None else
+                                          other.microsecond))
+
+    def __neg__(self):
+        return self.__class__(years=-self.years,
+                             months=-self.months,
+                             days=-self.days,
+                             hours=-self.hours,
+                             minutes=-self.minutes,
+                             seconds=-self.seconds,
+                             microseconds=-self.microseconds,
+                             leapdays=self.leapdays,
+                             year=self.year,
+                             month=self.month,
+                             day=self.day,
+                             weekday=self.weekday,
+                             hour=self.hour,
+                             minute=self.minute,
+                             second=self.second,
+                             microsecond=self.microsecond)
+
+    def __bool__(self):
+        return not (not self.years and
+                    not self.months and
+                    not self.days and
+                    not self.hours and
+                    not self.minutes and
+                    not self.seconds and
+                    not self.microseconds and
+                    not self.leapdays and
+                    self.year is None and
+                    self.month is None and
+                    self.day is None and
+                    self.weekday is None and
+                    self.hour is None and
+                    self.minute is None and
+                    self.second is None and
+                    self.microsecond is None)
+    # Compatibility with Python 2.x
+    __nonzero__ = __bool__
+
+    def __mul__(self, other):
+        try:
+            f = float(other)
+        except TypeError:
+            return NotImplemented
+
+        return self.__class__(years=int(self.years * f),
+                             months=int(self.months * f),
+                             days=int(self.days * f),
+                             hours=int(self.hours * f),
+                             minutes=int(self.minutes * f),
+                             seconds=int(self.seconds * f),
+                             microseconds=int(self.microseconds * f),
+                             leapdays=self.leapdays,
+                             year=self.year,
+                             month=self.month,
+                             day=self.day,
+                             weekday=self.weekday,
+                             hour=self.hour,
+                             minute=self.minute,
+                             second=self.second,
+                             microsecond=self.microsecond)
+
+    __rmul__ = __mul__
+
+    def __eq__(self, other):
+        if not isinstance(other, relativedelta):
+            return NotImplemented
+        if self.weekday or other.weekday:
+            if not self.weekday or not other.weekday:
+                return False
+            if self.weekday.weekday != other.weekday.weekday:
+                return False
+            n1, n2 = self.weekday.n, other.weekday.n
+            if n1 != n2 and not ((not n1 or n1 == 1) and (not n2 or n2 == 1)):
+                return False
+        return (self.years == other.years and
+                self.months == other.months and
+                self.days == other.days and
+                self.hours == other.hours and
+                self.minutes == other.minutes and
+                self.seconds == other.seconds and
+                self.microseconds == other.microseconds and
+                self.leapdays == other.leapdays and
+                self.year == other.year and
+                self.month == other.month and
+                self.day == other.day and
+                self.hour == other.hour and
+                self.minute == other.minute and
+                self.second == other.second and
+                self.microsecond == other.microsecond)
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+
+    def __div__(self, other):
+        try:
+            reciprocal = 1 / float(other)
+        except TypeError:
+            return NotImplemented
+
+        return self.__mul__(reciprocal)
+
+    __truediv__ = __div__
+
+    def __repr__(self):
+        l = []
+        for attr in ["years", "months", "days", "leapdays",
+                     "hours", "minutes", "seconds", "microseconds"]:
+            value = getattr(self, attr)
+            if value:
+                l.append("{attr}={value:+g}".format(attr=attr, value=value))
+        for attr in ["year", "month", "day", "weekday",
+                     "hour", "minute", "second", "microsecond"]:
+            value = getattr(self, attr)
+            if value is not None:
+                l.append("{attr}={value}".format(attr=attr, value=repr(value)))
+        return "{classname}({attrs})".format(classname=self.__class__.__name__,
+                                             attrs=", ".join(l))
+
+
+def _sign(x):
+    return int(copysign(1, x))
+
+# vim:ts=4:sw=4:et
diff --git a/python/dateutil/rrule.py b/python/dateutil/rrule.py
new file mode 100644
index 0000000..429f8fc
--- /dev/null
+++ b/python/dateutil/rrule.py
@@ -0,0 +1,1610 @@
+# -*- coding: utf-8 -*-
+"""
+The rrule module offers a small, complete, and very fast, implementation of
+the recurrence rules documented in the
+`iCalendar RFC <http://www.ietf.org/rfc/rfc2445.txt>`_,
+including support for caching of results.
+"""
+import itertools
+import datetime
+import calendar
+import sys
+
+try:
+    from math import gcd
+except ImportError:
+    from fractions import gcd
+
+from six import advance_iterator, integer_types
+from six.moves import _thread, range
+import heapq
+
+from ._common import weekday as weekdaybase
+
+# For warning about deprecation of until and count
+from warnings import warn
+
+__all__ = ["rrule", "rruleset", "rrulestr",
+           "YEARLY", "MONTHLY", "WEEKLY", "DAILY",
+           "HOURLY", "MINUTELY", "SECONDLY",
+           "MO", "TU", "WE", "TH", "FR", "SA", "SU"]
+
+# Every mask is 7 days longer to handle cross-year weekly periods.
+M366MASK = tuple([1]*31+[2]*29+[3]*31+[4]*30+[5]*31+[6]*30 +
+                 [7]*31+[8]*31+[9]*30+[10]*31+[11]*30+[12]*31+[1]*7)
+M365MASK = list(M366MASK)
+M29, M30, M31 = list(range(1, 30)), list(range(1, 31)), list(range(1, 32))
+MDAY366MASK = tuple(M31+M29+M31+M30+M31+M30+M31+M31+M30+M31+M30+M31+M31[:7])
+MDAY365MASK = list(MDAY366MASK)
+M29, M30, M31 = list(range(-29, 0)), list(range(-30, 0)), list(range(-31, 0))
+NMDAY366MASK = tuple(M31+M29+M31+M30+M31+M30+M31+M31+M30+M31+M30+M31+M31[:7])
+NMDAY365MASK = list(NMDAY366MASK)
+M366RANGE = (0, 31, 60, 91, 121, 152, 182, 213, 244, 274, 305, 335, 366)
+M365RANGE = (0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334, 365)
+WDAYMASK = [0, 1, 2, 3, 4, 5, 6]*55
+del M29, M30, M31, M365MASK[59], MDAY365MASK[59], NMDAY365MASK[31]
+MDAY365MASK = tuple(MDAY365MASK)
+M365MASK = tuple(M365MASK)
+
+FREQNAMES = ['YEARLY', 'MONTHLY', 'WEEKLY', 'DAILY', 'HOURLY', 'MINUTELY', 'SECONDLY']
+
+(YEARLY,
+ MONTHLY,
+ WEEKLY,
+ DAILY,
+ HOURLY,
+ MINUTELY,
+ SECONDLY) = list(range(7))
+
+# Imported on demand.
+easter = None
+parser = None
+
+
+class weekday(weekdaybase):
+    """
+    This version of weekday does not allow n = 0.
+    """
+    def __init__(self, wkday, n=None):
+        if n == 0:
+            raise ValueError("Can't create weekday with n==0")
+
+        super(weekday, self).__init__(wkday, n)
+
+
+MO, TU, WE, TH, FR, SA, SU = weekdays = tuple(weekday(x) for x in range(7))
+
+
+def _invalidates_cache(f):
+    """
+    Decorator for rruleset methods which may invalidate the
+    cached length.
+    """
+    def inner_func(self, *args, **kwargs):
+        rv = f(self, *args, **kwargs)
+        self._invalidate_cache()
+        return rv
+
+    return inner_func
+
+
+class rrulebase(object):
+    def __init__(self, cache=False):
+        if cache:
+            self._cache = []
+            self._cache_lock = _thread.allocate_lock()
+            self._invalidate_cache()
+        else:
+            self._cache = None
+            self._cache_complete = False
+            self._len = None
+
+    def __iter__(self):
+        if self._cache_complete:
+            return iter(self._cache)
+        elif self._cache is None:
+            return self._iter()
+        else:
+            return self._iter_cached()
+
+    def _invalidate_cache(self):
+        if self._cache is not None:
+            self._cache = []
+            self._cache_complete = False
+            self._cache_gen = self._iter()
+
+            if self._cache_lock.locked():
+                self._cache_lock.release()
+
+        self._len = None
+
+    def _iter_cached(self):
+        i = 0
+        gen = self._cache_gen
+        cache = self._cache
+        acquire = self._cache_lock.acquire
+        release = self._cache_lock.release
+        while gen:
+            if i == len(cache):
+                acquire()
+                if self._cache_complete:
+                    break
+                try:
+                    for j in range(10):
+                        cache.append(advance_iterator(gen))
+                except StopIteration:
+                    self._cache_gen = gen = None
+                    self._cache_complete = True
+                    break
+                release()
+            yield cache[i]
+            i += 1
+        while i < self._len:
+            yield cache[i]
+            i += 1
+
+    def __getitem__(self, item):
+        if self._cache_complete:
+            return self._cache[item]
+        elif isinstance(item, slice):
+            if item.step and item.step < 0:
+                return list(iter(self))[item]
+            else:
+                return list(itertools.islice(self,
+                                             item.start or 0,
+                                             item.stop or sys.maxsize,
+                                             item.step or 1))
+        elif item >= 0:
+            gen = iter(self)
+            try:
+                for i in range(item+1):
+                    res = advance_iterator(gen)
+            except StopIteration:
+                raise IndexError
+            return res
+        else:
+            return list(iter(self))[item]
+
+    def __contains__(self, item):
+        if self._cache_complete:
+            return item in self._cache
+        else:
+            for i in self:
+                if i == item:
+                    return True
+                elif i > item:
+                    return False
+        return False
+
+    # __len__() introduces a large performance penality.
+    def count(self):
+        """ Returns the number of recurrences in this set. It will have go
+            trough the whole recurrence, if this hasn't been done before. """
+        if self._len is None:
+            for x in self:
+                pass
+        return self._len
+
+    def before(self, dt, inc=False):
+        """ Returns the last recurrence before the given datetime instance. The
+            inc keyword defines what happens if dt is an occurrence. With
+            inc=True, if dt itself is an occurrence, it will be returned. """
+        if self._cache_complete:
+            gen = self._cache
+        else:
+            gen = self
+        last = None
+        if inc:
+            for i in gen:
+                if i > dt:
+                    break
+                last = i
+        else:
+            for i in gen:
+                if i >= dt:
+                    break
+                last = i
+        return last
+
+    def after(self, dt, inc=False):
+        """ Returns the first recurrence after the given datetime instance. The
+            inc keyword defines what happens if dt is an occurrence. With
+            inc=True, if dt itself is an occurrence, it will be returned.  """
+        if self._cache_complete:
+            gen = self._cache
+        else:
+            gen = self
+        if inc:
+            for i in gen:
+                if i >= dt:
+                    return i
+        else:
+            for i in gen:
+                if i > dt:
+                    return i
+        return None
+
+    def xafter(self, dt, count=None, inc=False):
+        """
+        Generator which yields up to `count` recurrences after the given
+        datetime instance, equivalent to `after`.
+
+        :param dt:
+            The datetime at which to start generating recurrences.
+
+        :param count:
+            The maximum number of recurrences to generate. If `None` (default),
+            dates are generated until the recurrence rule is exhausted.
+
+        :param inc:
+            If `dt` is an instance of the rule and `inc` is `True`, it is
+            included in the output.
+
+        :yields: Yields a sequence of `datetime` objects.
+        """
+
+        if self._cache_complete:
+            gen = self._cache
+        else:
+            gen = self
+
+        # Select the comparison function
+        if inc:
+            comp = lambda dc, dtc: dc >= dtc
+        else:
+            comp = lambda dc, dtc: dc > dtc
+
+        # Generate dates
+        n = 0
+        for d in gen:
+            if comp(d, dt):
+                if count is not None:
+                    n += 1
+                    if n > count:
+                        break
+
+                yield d
+
+    def between(self, after, before, inc=False, count=1):
+        """ Returns all the occurrences of the rrule between after and before.
+        The inc keyword defines what happens if after and/or before are
+        themselves occurrences. With inc=True, they will be included in the
+        list, if they are found in the recurrence set. """
+        if self._cache_complete:
+            gen = self._cache
+        else:
+            gen = self
+        started = False
+        l = []
+        if inc:
+            for i in gen:
+                if i > before:
+                    break
+                elif not started:
+                    if i >= after:
+                        started = True
+                        l.append(i)
+                else:
+                    l.append(i)
+        else:
+            for i in gen:
+                if i >= before:
+                    break
+                elif not started:
+                    if i > after:
+                        started = True
+                        l.append(i)
+                else:
+                    l.append(i)
+        return l
+
+
+class rrule(rrulebase):
+    """
+    That's the base of the rrule operation. It accepts all the keywords
+    defined in the RFC as its constructor parameters (except byday,
+    which was renamed to byweekday) and more. The constructor prototype is::
+
+            rrule(freq)
+
+    Where freq must be one of YEARLY, MONTHLY, WEEKLY, DAILY, HOURLY, MINUTELY,
+    or SECONDLY.
+
+    .. note::
+        Per RFC section 3.3.10, recurrence instances falling on invalid dates
+        and times are ignored rather than coerced:
+
+            Recurrence rules may generate recurrence instances with an invalid
+            date (e.g., February 30) or nonexistent local time (e.g., 1:30 AM
+            on a day where the local time is moved forward by an hour at 1:00
+            AM).  Such recurrence instances MUST be ignored and MUST NOT be
+            counted as part of the recurrence set.
+
+        This can lead to possibly surprising behavior when, for example, the
+        start date occurs at the end of the month:
+
+        >>> from dateutil.rrule import rrule, MONTHLY
+        >>> from datetime import datetime
+        >>> start_date = datetime(2014, 12, 31)
+        >>> list(rrule(freq=MONTHLY, count=4, dtstart=start_date))
+        ... # doctest: +NORMALIZE_WHITESPACE
+        [datetime.datetime(2014, 12, 31, 0, 0),
+         datetime.datetime(2015, 1, 31, 0, 0),
+         datetime.datetime(2015, 3, 31, 0, 0),
+         datetime.datetime(2015, 5, 31, 0, 0)]
+
+    Additionally, it supports the following keyword arguments:
+
+    :param cache:
+        If given, it must be a boolean value specifying to enable or disable
+        caching of results. If you will use the same rrule instance multiple
+        times, enabling caching will improve the performance considerably.
+    :param dtstart:
+        The recurrence start. Besides being the base for the recurrence,
+        missing parameters in the final recurrence instances will also be
+        extracted from this date. If not given, datetime.now() will be used
+        instead.
+    :param interval:
+        The interval between each freq iteration. For example, when using
+        YEARLY, an interval of 2 means once every two years, but with HOURLY,
+        it means once every two hours. The default interval is 1.
+    :param wkst:
+        The week start day. Must be one of the MO, TU, WE constants, or an
+        integer, specifying the first day of the week. This will affect
+        recurrences based on weekly periods. The default week start is got
+        from calendar.firstweekday(), and may be modified by
+        calendar.setfirstweekday().
+    :param count:
+        How many occurrences will be generated.
+
+        .. note::
+            As of version 2.5.0, the use of the ``until`` keyword together
+            with the ``count`` keyword is deprecated per RFC-2445 Sec. 4.3.10.
+    :param until:
+        If given, this must be a datetime instance, that will specify the
+        limit of the recurrence. The last recurrence in the rule is the greatest
+        datetime that is less than or equal to the value specified in the
+        ``until`` parameter.
+
+        .. note::
+            As of version 2.5.0, the use of the ``until`` keyword together
+            with the ``count`` keyword is deprecated per RFC-2445 Sec. 4.3.10.
+    :param bysetpos:
+        If given, it must be either an integer, or a sequence of integers,
+        positive or negative. Each given integer will specify an occurrence
+        number, corresponding to the nth occurrence of the rule inside the
+        frequency period. For example, a bysetpos of -1 if combined with a
+        MONTHLY frequency, and a byweekday of (MO, TU, WE, TH, FR), will
+        result in the last work day of every month.
+    :param bymonth:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the months to apply the recurrence to.
+    :param bymonthday:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the month days to apply the recurrence to.
+    :param byyearday:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the year days to apply the recurrence to.
+    :param byweekno:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the week numbers to apply the recurrence to. Week numbers
+        have the meaning described in ISO8601, that is, the first week of
+        the year is that containing at least four days of the new year.
+    :param byweekday:
+        If given, it must be either an integer (0 == MO), a sequence of
+        integers, one of the weekday constants (MO, TU, etc), or a sequence
+        of these constants. When given, these variables will define the
+        weekdays where the recurrence will be applied. It's also possible to
+        use an argument n for the weekday instances, which will mean the nth
+        occurrence of this weekday in the period. For example, with MONTHLY,
+        or with YEARLY and BYMONTH, using FR(+1) in byweekday will specify the
+        first friday of the month where the recurrence happens. Notice that in
+        the RFC documentation, this is specified as BYDAY, but was renamed to
+        avoid the ambiguity of that keyword.
+    :param byhour:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the hours to apply the recurrence to.
+    :param byminute:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the minutes to apply the recurrence to.
+    :param bysecond:
+        If given, it must be either an integer, or a sequence of integers,
+        meaning the seconds to apply the recurrence to.
+    :param byeaster:
+        If given, it must be either an integer, or a sequence of integers,
+        positive or negative. Each integer will define an offset from the
+        Easter Sunday. Passing the offset 0 to byeaster will yield the Easter
+        Sunday itself. This is an extension to the RFC specification.
+     """
+    def __init__(self, freq, dtstart=None,
+                 interval=1, wkst=None, count=None, until=None, bysetpos=None,
+                 bymonth=None, bymonthday=None, byyearday=None, byeaster=None,
+                 byweekno=None, byweekday=None,
+                 byhour=None, byminute=None, bysecond=None,
+                 cache=False):
+        super(rrule, self).__init__(cache)
+        global easter
+        if not dtstart:
+            dtstart = datetime.datetime.now().replace(microsecond=0)
+        elif not isinstance(dtstart, datetime.datetime):
+            dtstart = datetime.datetime.fromordinal(dtstart.toordinal())
+        else:
+            dtstart = dtstart.replace(microsecond=0)
+        self._dtstart = dtstart
+        self._tzinfo = dtstart.tzinfo
+        self._freq = freq
+        self._interval = interval
+        self._count = count
+
+        # Cache the original byxxx rules, if they are provided, as the _byxxx
+        # attributes do not necessarily map to the inputs, and this can be
+        # a problem in generating the strings. Only store things if they've
+        # been supplied (the string retrieval will just use .get())
+        self._original_rule = {}
+
+        if until and not isinstance(until, datetime.datetime):
+            until = datetime.datetime.fromordinal(until.toordinal())
+        self._until = until
+
+        if count is not None and until:
+            warn("Using both 'count' and 'until' is inconsistent with RFC 2445"
+                 " and has been deprecated in dateutil. Future versions will "
+                 "raise an error.", DeprecationWarning)
+
+        if wkst is None:
+            self._wkst = calendar.firstweekday()
+        elif isinstance(wkst, integer_types):
+            self._wkst = wkst
+        else:
+            self._wkst = wkst.weekday
+
+        if bysetpos is None:
+            self._bysetpos = None
+        elif isinstance(bysetpos, integer_types):
+            if bysetpos == 0 or not (-366 <= bysetpos <= 366):
+                raise ValueError("bysetpos must be between 1 and 366, "
+                                 "or between -366 and -1")
+            self._bysetpos = (bysetpos,)
+        else:
+            self._bysetpos = tuple(bysetpos)
+            for pos in self._bysetpos:
+                if pos == 0 or not (-366 <= pos <= 366):
+                    raise ValueError("bysetpos must be between 1 and 366, "
+                                     "or between -366 and -1")
+
+        if self._bysetpos:
+            self._original_rule['bysetpos'] = self._bysetpos
+
+        if (byweekno is None and byyearday is None and bymonthday is None and
+                byweekday is None and byeaster is None):
+            if freq == YEARLY:
+                if bymonth is None:
+                    bymonth = dtstart.month
+                    self._original_rule['bymonth'] = None
+                bymonthday = dtstart.day
+                self._original_rule['bymonthday'] = None
+            elif freq == MONTHLY:
+                bymonthday = dtstart.day
+                self._original_rule['bymonthday'] = None
+            elif freq == WEEKLY:
+                byweekday = dtstart.weekday()
+                self._original_rule['byweekday'] = None
+
+        # bymonth
+        if bymonth is None:
+            self._bymonth = None
+        else:
+            if isinstance(bymonth, integer_types):
+                bymonth = (bymonth,)
+
+            self._bymonth = tuple(sorted(set(bymonth)))
+
+            if 'bymonth' not in self._original_rule:
+                self._original_rule['bymonth'] = self._bymonth
+
+        # byyearday
+        if byyearday is None:
+            self._byyearday = None
+        else:
+            if isinstance(byyearday, integer_types):
+                byyearday = (byyearday,)
+
+            self._byyearday = tuple(sorted(set(byyearday)))
+            self._original_rule['byyearday'] = self._byyearday
+
+        # byeaster
+        if byeaster is not None:
+            if not easter:
+                from dateutil import easter
+            if isinstance(byeaster, integer_types):
+                self._byeaster = (byeaster,)
+            else:
+                self._byeaster = tuple(sorted(byeaster))
+
+            self._original_rule['byeaster'] = self._byeaster
+        else:
+            self._byeaster = None
+
+        # bymonthday
+        if bymonthday is None:
+            self._bymonthday = ()
+            self._bynmonthday = ()
+        else:
+            if isinstance(bymonthday, integer_types):
+                bymonthday = (bymonthday,)
+
+            bymonthday = set(bymonthday)            # Ensure it's unique
+
+            self._bymonthday = tuple(sorted(x for x in bymonthday if x > 0))
+            self._bynmonthday = tuple(sorted(x for x in bymonthday if x < 0))
+
+            # Storing positive numbers first, then negative numbers
+            if 'bymonthday' not in self._original_rule:
+                self._original_rule['bymonthday'] = tuple(
+                    itertools.chain(self._bymonthday, self._bynmonthday))
+
+        # byweekno
+        if byweekno is None:
+            self._byweekno = None
+        else:
+            if isinstance(byweekno, integer_types):
+                byweekno = (byweekno,)
+
+            self._byweekno = tuple(sorted(set(byweekno)))
+
+            self._original_rule['byweekno'] = self._byweekno
+
+        # byweekday / bynweekday
+        if byweekday is None:
+            self._byweekday = None
+            self._bynweekday = None
+        else:
+            # If it's one of the valid non-sequence types, convert to a
+            # single-element sequence before the iterator that builds the
+            # byweekday set.
+            if isinstance(byweekday, integer_types) or hasattr(byweekday, "n"):
+                byweekday = (byweekday,)
+
+            self._byweekday = set()
+            self._bynweekday = set()
+            for wday in byweekday:
+                if isinstance(wday, integer_types):
+                    self._byweekday.add(wday)
+                elif not wday.n or freq > MONTHLY:
+                    self._byweekday.add(wday.weekday)
+                else:
+                    self._bynweekday.add((wday.weekday, wday.n))
+
+            if not self._byweekday:
+                self._byweekday = None
+            elif not self._bynweekday:
+                self._bynweekday = None
+
+            if self._byweekday is not None:
+                self._byweekday = tuple(sorted(self._byweekday))
+                orig_byweekday = [weekday(x) for x in self._byweekday]
+            else:
+                orig_byweekday = tuple()
+
+            if self._bynweekday is not None:
+                self._bynweekday = tuple(sorted(self._bynweekday))
+                orig_bynweekday = [weekday(*x) for x in self._bynweekday]
+            else:
+                orig_bynweekday = tuple()
+
+            if 'byweekday' not in self._original_rule:
+                self._original_rule['byweekday'] = tuple(itertools.chain(
+                    orig_byweekday, orig_bynweekday))
+
+        # byhour
+        if byhour is None:
+            if freq < HOURLY:
+                self._byhour = set((dtstart.hour,))
+            else:
+                self._byhour = None
+        else:
+            if isinstance(byhour, integer_types):
+                byhour = (byhour,)
+
+            if freq == HOURLY:
+                self._byhour = self.__construct_byset(start=dtstart.hour,
+                                                      byxxx=byhour,
+                                                      base=24)
+            else:
+                self._byhour = set(byhour)
+
+            self._byhour = tuple(sorted(self._byhour))
+            self._original_rule['byhour'] = self._byhour
+
+        # byminute
+        if byminute is None:
+            if freq < MINUTELY:
+                self._byminute = set((dtstart.minute,))
+            else:
+                self._byminute = None
+        else:
+            if isinstance(byminute, integer_types):
+                byminute = (byminute,)
+
+            if freq == MINUTELY:
+                self._byminute = self.__construct_byset(start=dtstart.minute,
+                                                        byxxx=byminute,
+                                                        base=60)
+            else:
+                self._byminute = set(byminute)
+
+            self._byminute = tuple(sorted(self._byminute))
+            self._original_rule['byminute'] = self._byminute
+
+        # bysecond
+        if bysecond is None:
+            if freq < SECONDLY:
+                self._bysecond = ((dtstart.second,))
+            else:
+                self._bysecond = None
+        else:
+            if isinstance(bysecond, integer_types):
+                bysecond = (bysecond,)
+
+            self._bysecond = set(bysecond)
+
+            if freq == SECONDLY:
+                self._bysecond = self.__construct_byset(start=dtstart.second,
+                                                        byxxx=bysecond,
+                                                        base=60)
+            else:
+                self._bysecond = set(bysecond)
+
+            self._bysecond = tuple(sorted(self._bysecond))
+            self._original_rule['bysecond'] = self._bysecond
+
+        if self._freq >= HOURLY:
+            self._timeset = None
+        else:
+            self._timeset = []
+            for hour in self._byhour:
+                for minute in self._byminute:
+                    for second in self._bysecond:
+                        self._timeset.append(
+                            datetime.time(hour, minute, second,
+                                          tzinfo=self._tzinfo))
+            self._timeset.sort()
+            self._timeset = tuple(self._timeset)
+
+    def __str__(self):
+        """
+        Output a string that would generate this RRULE if passed to rrulestr.
+        This is mostly compatible with RFC2445, except for the
+        dateutil-specific extension BYEASTER.
+        """
+
+        output = []
+        h, m, s = [None] * 3
+        if self._dtstart:
+            output.append(self._dtstart.strftime('DTSTART:%Y%m%dT%H%M%S'))
+            h, m, s = self._dtstart.timetuple()[3:6]
+
+        parts = ['FREQ=' + FREQNAMES[self._freq]]
+        if self._interval != 1:
+            parts.append('INTERVAL=' + str(self._interval))
+
+        if self._wkst:
+            parts.append('WKST=' + repr(weekday(self._wkst))[0:2])
+
+        if self._count is not None:
+            parts.append('COUNT=' + str(self._count))
+
+        if self._until:
+            parts.append(self._until.strftime('UNTIL=%Y%m%dT%H%M%S'))
+
+        if self._original_rule.get('byweekday') is not None:
+            # The str() method on weekday objects doesn't generate
+            # RFC2445-compliant strings, so we should modify that.
+            original_rule = dict(self._original_rule)
+            wday_strings = []
+            for wday in original_rule['byweekday']:
+                if wday.n:
+                    wday_strings.append('{n:+d}{wday}'.format(
+                        n=wday.n,
+                        wday=repr(wday)[0:2]))
+                else:
+                    wday_strings.append(repr(wday))
+
+            original_rule['byweekday'] = wday_strings
+        else:
+            original_rule = self._original_rule
+
+        partfmt = '{name}={vals}'
+        for name, key in [('BYSETPOS', 'bysetpos'),
+                          ('BYMONTH', 'bymonth'),
+                          ('BYMONTHDAY', 'bymonthday'),
+                          ('BYYEARDAY', 'byyearday'),
+                          ('BYWEEKNO', 'byweekno'),
+                          ('BYDAY', 'byweekday'),
+                          ('BYHOUR', 'byhour'),
+                          ('BYMINUTE', 'byminute'),
+                          ('BYSECOND', 'bysecond'),
+                          ('BYEASTER', 'byeaster')]:
+            value = original_rule.get(key)
+            if value:
+                parts.append(partfmt.format(name=name, vals=(','.join(str(v)
+                                                             for v in value))))
+
+        output.append(';'.join(parts))
+        return '\n'.join(output)
+
+    def replace(self, **kwargs):
+        """Return new rrule with same attributes except for those attributes given new
+           values by whichever keyword arguments are specified."""
+        new_kwargs = {"interval": self._interval,
+                      "count": self._count,
+                      "dtstart": self._dtstart,
+                      "freq": self._freq,
+                      "until": self._until,
+                      "wkst": self._wkst,
+                      "cache": False if self._cache is None else True }
+        new_kwargs.update(self._original_rule)
+        new_kwargs.update(kwargs)
+        return rrule(**new_kwargs)
+
+    def _iter(self):
+        year, month, day, hour, minute, second, weekday, yearday, _ = \
+            self._dtstart.timetuple()
+
+        # Some local variables to speed things up a bit
+        freq = self._freq
+        interval = self._interval
+        wkst = self._wkst
+        until = self._until
+        bymonth = self._bymonth
+        byweekno = self._byweekno
+        byyearday = self._byyearday
+        byweekday = self._byweekday
+        byeaster = self._byeaster
+        bymonthday = self._bymonthday
+        bynmonthday = self._bynmonthday
+        bysetpos = self._bysetpos
+        byhour = self._byhour
+        byminute = self._byminute
+        bysecond = self._bysecond
+
+        ii = _iterinfo(self)
+        ii.rebuild(year, month)
+
+        getdayset = {YEARLY: ii.ydayset,
+                     MONTHLY: ii.mdayset,
+                     WEEKLY: ii.wdayset,
+                     DAILY: ii.ddayset,
+                     HOURLY: ii.ddayset,
+                     MINUTELY: ii.ddayset,
+                     SECONDLY: ii.ddayset}[freq]
+
+        if freq < HOURLY:
+            timeset = self._timeset
+        else:
+            gettimeset = {HOURLY: ii.htimeset,
+                          MINUTELY: ii.mtimeset,
+                          SECONDLY: ii.stimeset}[freq]
+            if ((freq >= HOURLY and
+                 self._byhour and hour not in self._byhour) or
+                (freq >= MINUTELY and
+                 self._byminute and minute not in self._byminute) or
+                (freq >= SECONDLY and
+                 self._bysecond and second not in self._bysecond)):
+                timeset = ()
+            else:
+                timeset = gettimeset(hour, minute, second)
+
+        total = 0
+        count = self._count
+        while True:
+            # Get dayset with the right frequency
+            dayset, start, end = getdayset(year, month, day)
+
+            # Do the "hard" work ;-)
+            filtered = False
+            for i in dayset[start:end]:
+                if ((bymonth and ii.mmask[i] not in bymonth) or
+                    (byweekno and not ii.wnomask[i]) or
+                    (byweekday and ii.wdaymask[i] not in byweekday) or
+                    (ii.nwdaymask and not ii.nwdaymask[i]) or
+                    (byeaster and not ii.eastermask[i]) or
+                    ((bymonthday or bynmonthday) and
+                     ii.mdaymask[i] not in bymonthday and
+                     ii.nmdaymask[i] not in bynmonthday) or
+                    (byyearday and
+                     ((i < ii.yearlen and i+1 not in byyearday and
+                       -ii.yearlen+i not in byyearday) or
+                      (i >= ii.yearlen and i+1-ii.yearlen not in byyearday and
+                       -ii.nextyearlen+i-ii.yearlen not in byyearday)))):
+                    dayset[i] = None
+                    filtered = True
+
+            # Output results
+            if bysetpos and timeset:
+                poslist = []
+                for pos in bysetpos:
+                    if pos < 0:
+                        daypos, timepos = divmod(pos, len(timeset))
+                    else:
+                        daypos, timepos = divmod(pos-1, len(timeset))
+                    try:
+                        i = [x for x in dayset[start:end]
+                             if x is not None][daypos]
+                        time = timeset[timepos]
+                    except IndexError:
+                        pass
+                    else:
+                        date = datetime.date.fromordinal(ii.yearordinal+i)
+                        res = datetime.datetime.combine(date, time)
+                        if res not in poslist:
+                            poslist.append(res)
+                poslist.sort()
+                for res in poslist:
+                    if until and res > until:
+                        self._len = total
+                        return
+                    elif res >= self._dtstart:
+                        if count is not None:
+                            count -= 1
+                            if count < 0:
+                                self._len = total
+                                return
+                        total += 1
+                        yield res
+            else:
+                for i in dayset[start:end]:
+                    if i is not None:
+                        date = datetime.date.fromordinal(ii.yearordinal + i)
+                        for time in timeset:
+                            res = datetime.datetime.combine(date, time)
+                            if until and res > until:
+                                self._len = total
+                                return
+                            elif res >= self._dtstart:
+                                if count is not None:
+                                    count -= 1
+                                    if count < 0:
+                                        self._len = total
+                                        return
+
+                                total += 1
+                                yield res
+
+            # Handle frequency and interval
+            fixday = False
+            if freq == YEARLY:
+                year += interval
+                if year > datetime.MAXYEAR:
+                    self._len = total
+                    return
+                ii.rebuild(year, month)
+            elif freq == MONTHLY:
+                month += interval
+                if month > 12:
+                    div, mod = divmod(month, 12)
+                    month = mod
+                    year += div
+                    if month == 0:
+                        month = 12
+                        year -= 1
+                    if year > datetime.MAXYEAR:
+                        self._len = total
+                        return
+                ii.rebuild(year, month)
+            elif freq == WEEKLY:
+                if wkst > weekday:
+                    day += -(weekday+1+(6-wkst))+self._interval*7
+                else:
+                    day += -(weekday-wkst)+self._interval*7
+                weekday = wkst
+                fixday = True
+            elif freq == DAILY:
+                day += interval
+                fixday = True
+            elif freq == HOURLY:
+                if filtered:
+                    # Jump to one iteration before next day
+                    hour += ((23-hour)//interval)*interval
+
+                if byhour:
+                    ndays, hour = self.__mod_distance(value=hour,
+                                                      byxxx=self._byhour,
+                                                      base=24)
+                else:
+                    ndays, hour = divmod(hour+interval, 24)
+
+                if ndays:
+                    day += ndays
+                    fixday = True
+
+                timeset = gettimeset(hour, minute, second)
+            elif freq == MINUTELY:
+                if filtered:
+                    # Jump to one iteration before next day
+                    minute += ((1439-(hour*60+minute))//interval)*interval
+
+                valid = False
+                rep_rate = (24*60)
+                for j in range(rep_rate // gcd(interval, rep_rate)):
+                    if byminute:
+                        nhours, minute = \
+                            self.__mod_distance(value=minute,
+                                                byxxx=self._byminute,
+                                                base=60)
+                    else:
+                        nhours, minute = divmod(minute+interval, 60)
+
+                    div, hour = divmod(hour+nhours, 24)
+                    if div:
+                        day += div
+                        fixday = True
+                        filtered = False
+
+                    if not byhour or hour in byhour:
+                        valid = True
+                        break
+
+                if not valid:
+                    raise ValueError('Invalid combination of interval and ' +
+                                     'byhour resulting in empty rule.')
+
+                timeset = gettimeset(hour, minute, second)
+            elif freq == SECONDLY:
+                if filtered:
+                    # Jump to one iteration before next day
+                    second += (((86399 - (hour * 3600 + minute * 60 + second))
+                                // interval) * interval)
+
+                rep_rate = (24 * 3600)
+                valid = False
+                for j in range(0, rep_rate // gcd(interval, rep_rate)):
+                    if bysecond:
+                        nminutes, second = \
+                            self.__mod_distance(value=second,
+                                                byxxx=self._bysecond,
+                                                base=60)
+                    else:
+                        nminutes, second = divmod(second+interval, 60)
+
+                    div, minute = divmod(minute+nminutes, 60)
+                    if div:
+                        hour += div
+                        div, hour = divmod(hour, 24)
+                        if div:
+                            day += div
+                            fixday = True
+
+                    if ((not byhour or hour in byhour) and
+                            (not byminute or minute in byminute) and
+                            (not bysecond or second in bysecond)):
+                        valid = True
+                        break
+
+                if not valid:
+                    raise ValueError('Invalid combination of interval, ' +
+                                     'byhour and byminute resulting in empty' +
+                                     ' rule.')
+
+                timeset = gettimeset(hour, minute, second)
+
+            if fixday and day > 28:
+                daysinmonth = calendar.monthrange(year, month)[1]
+                if day > daysinmonth:
+                    while day > daysinmonth:
+                        day -= daysinmonth
+                        month += 1
+                        if month == 13:
+                            month = 1
+                            year += 1
+                            if year > datetime.MAXYEAR:
+                                self._len = total
+                                return
+                        daysinmonth = calendar.monthrange(year, month)[1]
+                    ii.rebuild(year, month)
+
+    def __construct_byset(self, start, byxxx, base):
+        """
+        If a `BYXXX` sequence is passed to the constructor at the same level as
+        `FREQ` (e.g. `FREQ=HOURLY,BYHOUR={2,4,7},INTERVAL=3`), there are some
+        specifications which cannot be reached given some starting conditions.
+
+        This occurs whenever the interval is not coprime with the base of a
+        given unit and the difference between the starting position and the
+        ending position is not coprime with the greatest common denominator
+        between the interval and the base. For example, with a FREQ of hourly
+        starting at 17:00 and an interval of 4, the only valid values for
+        BYHOUR would be {21, 1, 5, 9, 13, 17}, because 4 and 24 are not
+        coprime.
+
+        :param start:
+            Specifies the starting position.
+        :param byxxx:
+            An iterable containing the list of allowed values.
+        :param base:
+            The largest allowable value for the specified frequency (e.g.
+            24 hours, 60 minutes).
+
+        This does not preserve the type of the iterable, returning a set, since
+        the values should be unique and the order is irrelevant, this will
+        speed up later lookups.
+
+        In the event of an empty set, raises a :exception:`ValueError`, as this
+        results in an empty rrule.
+        """
+
+        cset = set()
+
+        # Support a single byxxx value.
+        if isinstance(byxxx, integer_types):
+            byxxx = (byxxx, )
+
+        for num in byxxx:
+            i_gcd = gcd(self._interval, base)
+            # Use divmod rather than % because we need to wrap negative nums.
+            if i_gcd == 1 or divmod(num - start, i_gcd)[1] == 0:
+                cset.add(num)
+
+        if len(cset) == 0:
+            raise ValueError("Invalid rrule byxxx generates an empty set.")
+
+        return cset
+
+    def __mod_distance(self, value, byxxx, base):
+        """
+        Calculates the next value in a sequence where the `FREQ` parameter is
+        specified along with a `BYXXX` parameter at the same "level"
+        (e.g. `HOURLY` specified with `BYHOUR`).
+
+        :param value:
+            The old value of the component.
+        :param byxxx:
+            The `BYXXX` set, which should have been generated by
+            `rrule._construct_byset`, or something else which checks that a
+            valid rule is present.
+        :param base:
+            The largest allowable value for the specified frequency (e.g.
+            24 hours, 60 minutes).
+
+        If a valid value is not found after `base` iterations (the maximum
+        number before the sequence would start to repeat), this raises a
+        :exception:`ValueError`, as no valid values were found.
+
+        This returns a tuple of `divmod(n*interval, base)`, where `n` is the
+        smallest number of `interval` repetitions until the next specified
+        value in `byxxx` is found.
+        """
+        accumulator = 0
+        for ii in range(1, base + 1):
+            # Using divmod() over % to account for negative intervals
+            div, value = divmod(value + self._interval, base)
+            accumulator += div
+            if value in byxxx:
+                return (accumulator, value)
+
+
+class _iterinfo(object):
+    __slots__ = ["rrule", "lastyear", "lastmonth",
+                 "yearlen", "nextyearlen", "yearordinal", "yearweekday",
+                 "mmask", "mrange", "mdaymask", "nmdaymask",
+                 "wdaymask", "wnomask", "nwdaymask", "eastermask"]
+
+    def __init__(self, rrule):
+        for attr in self.__slots__:
+            setattr(self, attr, None)
+        self.rrule = rrule
+
+    def rebuild(self, year, month):
+        # Every mask is 7 days longer to handle cross-year weekly periods.
+        rr = self.rrule
+        if year != self.lastyear:
+            self.yearlen = 365 + calendar.isleap(year)
+            self.nextyearlen = 365 + calendar.isleap(year + 1)
+            firstyday = datetime.date(year, 1, 1)
+            self.yearordinal = firstyday.toordinal()
+            self.yearweekday = firstyday.weekday()
+
+            wday = datetime.date(year, 1, 1).weekday()
+            if self.yearlen == 365:
+                self.mmask = M365MASK
+                self.mdaymask = MDAY365MASK
+                self.nmdaymask = NMDAY365MASK
+                self.wdaymask = WDAYMASK[wday:]
+                self.mrange = M365RANGE
+            else:
+                self.mmask = M366MASK
+                self.mdaymask = MDAY366MASK
+                self.nmdaymask = NMDAY366MASK
+                self.wdaymask = WDAYMASK[wday:]
+                self.mrange = M366RANGE
+
+            if not rr._byweekno:
+                self.wnomask = None
+            else:
+                self.wnomask = [0]*(self.yearlen+7)
+                # no1wkst = firstwkst = self.wdaymask.index(rr._wkst)
+                no1wkst = firstwkst = (7-self.yearweekday+rr._wkst) % 7
+                if no1wkst >= 4:
+                    no1wkst = 0
+                    # Number of days in the year, plus the days we got
+                    # from last year.
+                    wyearlen = self.yearlen+(self.yearweekday-rr._wkst) % 7
+                else:
+                    # Number of days in the year, minus the days we
+                    # left in last year.
+                    wyearlen = self.yearlen-no1wkst
+                div, mod = divmod(wyearlen, 7)
+                numweeks = div+mod//4
+                for n in rr._byweekno:
+                    if n < 0:
+                        n += numweeks+1
+                    if not (0 < n <= numweeks):
+                        continue
+                    if n > 1:
+                        i = no1wkst+(n-1)*7
+                        if no1wkst != firstwkst:
+                            i -= 7-firstwkst
+                    else:
+                        i = no1wkst
+                    for j in range(7):
+                        self.wnomask[i] = 1
+                        i += 1
+                        if self.wdaymask[i] == rr._wkst:
+                            break
+                if 1 in rr._byweekno:
+                    # Check week number 1 of next year as well
+                    # TODO: Check -numweeks for next year.
+                    i = no1wkst+numweeks*7
+                    if no1wkst != firstwkst:
+                        i -= 7-firstwkst
+                    if i < self.yearlen:
+                        # If week starts in next year, we
+                        # don't care about it.
+                        for j in range(7):
+                            self.wnomask[i] = 1
+                            i += 1
+                            if self.wdaymask[i] == rr._wkst:
+                                break
+                if no1wkst:
+                    # Check last week number of last year as
+                    # well. If no1wkst is 0, either the year
+                    # started on week start, or week number 1
+                    # got days from last year, so there are no
+                    # days from last year's last week number in
+                    # this year.
+                    if -1 not in rr._byweekno:
+                        lyearweekday = datetime.date(year-1, 1, 1).weekday()
+                        lno1wkst = (7-lyearweekday+rr._wkst) % 7
+                        lyearlen = 365+calendar.isleap(year-1)
+                        if lno1wkst >= 4:
+                            lno1wkst = 0
+                            lnumweeks = 52+(lyearlen +
+                                            (lyearweekday-rr._wkst) % 7) % 7//4
+                        else:
+                            lnumweeks = 52+(self.yearlen-no1wkst) % 7//4
+                    else:
+                        lnumweeks = -1
+                    if lnumweeks in rr._byweekno:
+                        for i in range(no1wkst):
+                            self.wnomask[i] = 1
+
+        if (rr._bynweekday and (month != self.lastmonth or
+                                year != self.lastyear)):
+            ranges = []
+            if rr._freq == YEARLY:
+                if rr._bymonth:
+                    for month in rr._bymonth:
+                        ranges.append(self.mrange[month-1:month+1])
+                else:
+                    ranges = [(0, self.yearlen)]
+            elif rr._freq == MONTHLY:
+                ranges = [self.mrange[month-1:month+1]]
+            if ranges:
+                # Weekly frequency won't get here, so we may not
+                # care about cross-year weekly periods.
+                self.nwdaymask = [0]*self.yearlen
+                for first, last in ranges:
+                    last -= 1
+                    for wday, n in rr._bynweekday:
+                        if n < 0:
+                            i = last+(n+1)*7
+                            i -= (self.wdaymask[i]-wday) % 7
+                        else:
+                            i = first+(n-1)*7
+                            i += (7-self.wdaymask[i]+wday) % 7
+                        if first <= i <= last:
+                            self.nwdaymask[i] = 1
+
+        if rr._byeaster:
+            self.eastermask = [0]*(self.yearlen+7)
+            eyday = easter.easter(year).toordinal()-self.yearordinal
+            for offset in rr._byeaster:
+                self.eastermask[eyday+offset] = 1
+
+        self.lastyear = year
+        self.lastmonth = month
+
+    def ydayset(self, year, month, day):
+        return list(range(self.yearlen)), 0, self.yearlen
+
+    def mdayset(self, year, month, day):
+        dset = [None]*self.yearlen
+        start, end = self.mrange[month-1:month+1]
+        for i in range(start, end):
+            dset[i] = i
+        return dset, start, end
+
+    def wdayset(self, year, month, day):
+        # We need to handle cross-year weeks here.
+        dset = [None]*(self.yearlen+7)
+        i = datetime.date(year, month, day).toordinal()-self.yearordinal
+        start = i
+        for j in range(7):
+            dset[i] = i
+            i += 1
+            # if (not (0 <= i < self.yearlen) or
+            #    self.wdaymask[i] == self.rrule._wkst):
+            # This will cross the year boundary, if necessary.
+            if self.wdaymask[i] == self.rrule._wkst:
+                break
+        return dset, start, i
+
+    def ddayset(self, year, month, day):
+        dset = [None] * self.yearlen
+        i = datetime.date(year, month, day).toordinal() - self.yearordinal
+        dset[i] = i
+        return dset, i, i + 1
+
+    def htimeset(self, hour, minute, second):
+        tset = []
+        rr = self.rrule
+        for minute in rr._byminute:
+            for second in rr._bysecond:
+                tset.append(datetime.time(hour, minute, second,
+                                          tzinfo=rr._tzinfo))
+        tset.sort()
+        return tset
+
+    def mtimeset(self, hour, minute, second):
+        tset = []
+        rr = self.rrule
+        for second in rr._bysecond:
+            tset.append(datetime.time(hour, minute, second, tzinfo=rr._tzinfo))
+        tset.sort()
+        return tset
+
+    def stimeset(self, hour, minute, second):
+        return (datetime.time(hour, minute, second,
+                tzinfo=self.rrule._tzinfo),)
+
+
+class rruleset(rrulebase):
+    """ The rruleset type allows more complex recurrence setups, mixing
+    multiple rules, dates, exclusion rules, and exclusion dates. The type
+    constructor takes the following keyword arguments:
+
+    :param cache: If True, caching of results will be enabled, improving
+                  performance of multiple queries considerably. """
+
+    class _genitem(object):
+        def __init__(self, genlist, gen):
+            try:
+                self.dt = advance_iterator(gen)
+                genlist.append(self)
+            except StopIteration:
+                pass
+            self.genlist = genlist
+            self.gen = gen
+
+        def __next__(self):
+            try:
+                self.dt = advance_iterator(self.gen)
+            except StopIteration:
+                if self.genlist[0] is self:
+                    heapq.heappop(self.genlist)
+                else:
+                    self.genlist.remove(self)
+                    heapq.heapify(self.genlist)
+
+        next = __next__
+
+        def __lt__(self, other):
+            return self.dt < other.dt
+
+        def __gt__(self, other):
+            return self.dt > other.dt
+
+        def __eq__(self, other):
+            return self.dt == other.dt
+
+        def __ne__(self, other):
+            return self.dt != other.dt
+
+    def __init__(self, cache=False):
+        super(rruleset, self).__init__(cache)
+        self._rrule = []
+        self._rdate = []
+        self._exrule = []
+        self._exdate = []
+
+    @_invalidates_cache
+    def rrule(self, rrule):
+        """ Include the given :py:class:`rrule` instance in the recurrence set
+            generation. """
+        self._rrule.append(rrule)
+
+    @_invalidates_cache
+    def rdate(self, rdate):
+        """ Include the given :py:class:`datetime` instance in the recurrence
+            set generation. """
+        self._rdate.append(rdate)
+
+    @_invalidates_cache
+    def exrule(self, exrule):
+        """ Include the given rrule instance in the recurrence set exclusion
+            list. Dates which are part of the given recurrence rules will not
+            be generated, even if some inclusive rrule or rdate matches them.
+        """
+        self._exrule.append(exrule)
+
+    @_invalidates_cache
+    def exdate(self, exdate):
+        """ Include the given datetime instance in the recurrence set
+            exclusion list. Dates included that way will not be generated,
+            even if some inclusive rrule or rdate matches them. """
+        self._exdate.append(exdate)
+
+    def _iter(self):
+        rlist = []
+        self._rdate.sort()
+        self._genitem(rlist, iter(self._rdate))
+        for gen in [iter(x) for x in self._rrule]:
+            self._genitem(rlist, gen)
+        exlist = []
+        self._exdate.sort()
+        self._genitem(exlist, iter(self._exdate))
+        for gen in [iter(x) for x in self._exrule]:
+            self._genitem(exlist, gen)
+        lastdt = None
+        total = 0
+        heapq.heapify(rlist)
+        heapq.heapify(exlist)
+        while rlist:
+            ritem = rlist[0]
+            if not lastdt or lastdt != ritem.dt:
+                while exlist and exlist[0] < ritem:
+                    exitem = exlist[0]
+                    advance_iterator(exitem)
+                    if exlist and exlist[0] is exitem:
+                        heapq.heapreplace(exlist, exitem)
+                if not exlist or ritem != exlist[0]:
+                    total += 1
+                    yield ritem.dt
+                lastdt = ritem.dt
+            advance_iterator(ritem)
+            if rlist and rlist[0] is ritem:
+                heapq.heapreplace(rlist, ritem)
+        self._len = total
+
+
+class _rrulestr(object):
+
+    _freq_map = {"YEARLY": YEARLY,
+                 "MONTHLY": MONTHLY,
+                 "WEEKLY": WEEKLY,
+                 "DAILY": DAILY,
+                 "HOURLY": HOURLY,
+                 "MINUTELY": MINUTELY,
+                 "SECONDLY": SECONDLY}
+
+    _weekday_map = {"MO": 0, "TU": 1, "WE": 2, "TH": 3,
+                    "FR": 4, "SA": 5, "SU": 6}
+
+    def _handle_int(self, rrkwargs, name, value, **kwargs):
+        rrkwargs[name.lower()] = int(value)
+
+    def _handle_int_list(self, rrkwargs, name, value, **kwargs):
+        rrkwargs[name.lower()] = [int(x) for x in value.split(',')]
+
+    _handle_INTERVAL = _handle_int
+    _handle_COUNT = _handle_int
+    _handle_BYSETPOS = _handle_int_list
+    _handle_BYMONTH = _handle_int_list
+    _handle_BYMONTHDAY = _handle_int_list
+    _handle_BYYEARDAY = _handle_int_list
+    _handle_BYEASTER = _handle_int_list
+    _handle_BYWEEKNO = _handle_int_list
+    _handle_BYHOUR = _handle_int_list
+    _handle_BYMINUTE = _handle_int_list
+    _handle_BYSECOND = _handle_int_list
+
+    def _handle_FREQ(self, rrkwargs, name, value, **kwargs):
+        rrkwargs["freq"] = self._freq_map[value]
+
+    def _handle_UNTIL(self, rrkwargs, name, value, **kwargs):
+        global parser
+        if not parser:
+            from dateutil import parser
+        try:
+            rrkwargs["until"] = parser.parse(value,
+                                             ignoretz=kwargs.get("ignoretz"),
+                                             tzinfos=kwargs.get("tzinfos"))
+        except ValueError:
+            raise ValueError("invalid until date")
+
+    def _handle_WKST(self, rrkwargs, name, value, **kwargs):
+        rrkwargs["wkst"] = self._weekday_map[value]
+
+    def _handle_BYWEEKDAY(self, rrkwargs, name, value, **kwargs):
+        """
+        Two ways to specify this: +1MO or MO(+1)
+        """
+        l = []
+        for wday in value.split(','):
+            if '(' in wday:
+                # If it's of the form TH(+1), etc.
+                splt = wday.split('(')
+                w = splt[0]
+                n = int(splt[1][:-1])
+            elif len(wday):
+                # If it's of the form +1MO
+                for i in range(len(wday)):
+                    if wday[i] not in '+-0123456789':
+                        break
+                n = wday[:i] or None
+                w = wday[i:]
+                if n:
+                    n = int(n)
+            else:
+                raise ValueError("Invalid (empty) BYDAY specification.")
+
+            l.append(weekdays[self._weekday_map[w]](n))
+        rrkwargs["byweekday"] = l
+
+    _handle_BYDAY = _handle_BYWEEKDAY
+
+    def _parse_rfc_rrule(self, line,
+                         dtstart=None,
+                         cache=False,
+                         ignoretz=False,
+                         tzinfos=None):
+        if line.find(':') != -1:
+            name, value = line.split(':')
+            if name != "RRULE":
+                raise ValueError("unknown parameter name")
+        else:
+            value = line
+        rrkwargs = {}
+        for pair in value.split(';'):
+            name, value = pair.split('=')
+            name = name.upper()
+            value = value.upper()
+            try:
+                getattr(self, "_handle_"+name)(rrkwargs, name, value,
+                                               ignoretz=ignoretz,
+                                               tzinfos=tzinfos)
+            except AttributeError:
+                raise ValueError("unknown parameter '%s'" % name)
+            except (KeyError, ValueError):
+                raise ValueError("invalid '%s': %s" % (name, value))
+        return rrule(dtstart=dtstart, cache=cache, **rrkwargs)
+
+    def _parse_rfc(self, s,
+                   dtstart=None,
+                   cache=False,
+                   unfold=False,
+                   forceset=False,
+                   compatible=False,
+                   ignoretz=False,
+                   tzinfos=None):
+        global parser
+        if compatible:
+            forceset = True
+            unfold = True
+        s = s.upper()
+        if not s.strip():
+            raise ValueError("empty string")
+        if unfold:
+            lines = s.splitlines()
+            i = 0
+            while i < len(lines):
+                line = lines[i].rstrip()
+                if not line:
+                    del lines[i]
+                elif i > 0 and line[0] == " ":
+                    lines[i-1] += line[1:]
+                    del lines[i]
+                else:
+                    i += 1
+        else:
+            lines = s.split()
+        if (not forceset and len(lines) == 1 and (s.find(':') == -1 or
+                                                  s.startswith('RRULE:'))):
+            return self._parse_rfc_rrule(lines[0], cache=cache,
+                                         dtstart=dtstart, ignoretz=ignoretz,
+                                         tzinfos=tzinfos)
+        else:
+            rrulevals = []
+            rdatevals = []
+            exrulevals = []
+            exdatevals = []
+            for line in lines:
+                if not line:
+                    continue
+                if line.find(':') == -1:
+                    name = "RRULE"
+                    value = line
+                else:
+                    name, value = line.split(':', 1)
+                parms = name.split(';')
+                if not parms:
+                    raise ValueError("empty property name")
+                name = parms[0]
+                parms = parms[1:]
+                if name == "RRULE":
+                    for parm in parms:
+                        raise ValueError("unsupported RRULE parm: "+parm)
+                    rrulevals.append(value)
+                elif name == "RDATE":
+                    for parm in parms:
+                        if parm != "VALUE=DATE-TIME":
+                            raise ValueError("unsupported RDATE parm: "+parm)
+                    rdatevals.append(value)
+                elif name == "EXRULE":
+                    for parm in parms:
+                        raise ValueError("unsupported EXRULE parm: "+parm)
+                    exrulevals.append(value)
+                elif name == "EXDATE":
+                    for parm in parms:
+                        if parm != "VALUE=DATE-TIME":
+                            raise ValueError("unsupported EXDATE parm: "+parm)
+                    exdatevals.append(value)
+                elif name == "DTSTART":
+                    for parm in parms:
+                        raise ValueError("unsupported DTSTART parm: "+parm)
+                    if not parser:
+                        from dateutil import parser
+                    dtstart = parser.parse(value, ignoretz=ignoretz,
+                                           tzinfos=tzinfos)
+                else:
+                    raise ValueError("unsupported property: "+name)
+            if (forceset or len(rrulevals) > 1 or rdatevals
+                    or exrulevals or exdatevals):
+                if not parser and (rdatevals or exdatevals):
+                    from dateutil import parser
+                rset = rruleset(cache=cache)
+                for value in rrulevals:
+                    rset.rrule(self._parse_rfc_rrule(value, dtstart=dtstart,
+                                                     ignoretz=ignoretz,
+                                                     tzinfos=tzinfos))
+                for value in rdatevals:
+                    for datestr in value.split(','):
+                        rset.rdate(parser.parse(datestr,
+                                                ignoretz=ignoretz,
+                                                tzinfos=tzinfos))
+                for value in exrulevals:
+                    rset.exrule(self._parse_rfc_rrule(value, dtstart=dtstart,
+                                                      ignoretz=ignoretz,
+                                                      tzinfos=tzinfos))
+                for value in exdatevals:
+                    for datestr in value.split(','):
+                        rset.exdate(parser.parse(datestr,
+                                                 ignoretz=ignoretz,
+                                                 tzinfos=tzinfos))
+                if compatible and dtstart:
+                    rset.rdate(dtstart)
+                return rset
+            else:
+                return self._parse_rfc_rrule(rrulevals[0],
+                                             dtstart=dtstart,
+                                             cache=cache,
+                                             ignoretz=ignoretz,
+                                             tzinfos=tzinfos)
+
+    def __call__(self, s, **kwargs):
+        return self._parse_rfc(s, **kwargs)
+
+
+rrulestr = _rrulestr()
+
+# vim:ts=4:sw=4:et
diff --git a/python/dateutil/tz/__init__.py b/python/dateutil/tz/__init__.py
new file mode 100644
index 0000000..b0a5043
--- /dev/null
+++ b/python/dateutil/tz/__init__.py
@@ -0,0 +1,5 @@
+from .tz import *
+
+__all__ = ["tzutc", "tzoffset", "tzlocal", "tzfile", "tzrange",
+           "tzstr", "tzical", "tzwin", "tzwinlocal", "gettz",
+           "enfold", "datetime_ambiguous", "datetime_exists"]
diff --git a/python/dateutil/tz/_common.py b/python/dateutil/tz/_common.py
new file mode 100644
index 0000000..f1cf2af
--- /dev/null
+++ b/python/dateutil/tz/_common.py
@@ -0,0 +1,394 @@
+from six import PY3
+
+from functools import wraps
+
+from datetime import datetime, timedelta, tzinfo
+
+
+ZERO = timedelta(0)
+
+__all__ = ['tzname_in_python2', 'enfold']
+
+
+def tzname_in_python2(namefunc):
+    """Change unicode output into bytestrings in Python 2
+
+    tzname() API changed in Python 3. It used to return bytes, but was changed
+    to unicode strings
+    """
+    def adjust_encoding(*args, **kwargs):
+        name = namefunc(*args, **kwargs)
+        if name is not None and not PY3:
+            name = name.encode()
+
+        return name
+
+    return adjust_encoding
+
+
+# The following is adapted from Alexander Belopolsky's tz library
+# https://github.com/abalkin/tz
+if hasattr(datetime, 'fold'):
+    # This is the pre-python 3.6 fold situation
+    def enfold(dt, fold=1):
+        """
+        Provides a unified interface for assigning the ``fold`` attribute to
+        datetimes both before and after the implementation of PEP-495.
+
+        :param fold:
+            The value for the ``fold`` attribute in the returned datetime. This
+            should be either 0 or 1.
+
+        :return:
+            Returns an object for which ``getattr(dt, 'fold', 0)`` returns
+            ``fold`` for all versions of Python. In versions prior to
+            Python 3.6, this is a ``_DatetimeWithFold`` object, which is a
+            subclass of :py:class:`datetime.datetime` with the ``fold``
+            attribute added, if ``fold`` is 1.
+
+        .. versionadded:: 2.6.0
+        """
+        return dt.replace(fold=fold)
+
+else:
+    class _DatetimeWithFold(datetime):
+        """
+        This is a class designed to provide a PEP 495-compliant interface for
+        Python versions before 3.6. It is used only for dates in a fold, so
+        the ``fold`` attribute is fixed at ``1``.
+
+        .. versionadded:: 2.6.0
+        """
+        __slots__ = ()
+
+        @property
+        def fold(self):
+            return 1
+
+    def enfold(dt, fold=1):
+        """
+        Provides a unified interface for assigning the ``fold`` attribute to
+        datetimes both before and after the implementation of PEP-495.
+
+        :param fold:
+            The value for the ``fold`` attribute in the returned datetime. This
+            should be either 0 or 1.
+
+        :return:
+            Returns an object for which ``getattr(dt, 'fold', 0)`` returns
+            ``fold`` for all versions of Python. In versions prior to
+            Python 3.6, this is a ``_DatetimeWithFold`` object, which is a
+            subclass of :py:class:`datetime.datetime` with the ``fold``
+            attribute added, if ``fold`` is 1.
+
+        .. versionadded:: 2.6.0
+        """
+        if getattr(dt, 'fold', 0) == fold:
+            return dt
+
+        args = dt.timetuple()[:6]
+        args += (dt.microsecond, dt.tzinfo)
+
+        if fold:
+            return _DatetimeWithFold(*args)
+        else:
+            return datetime(*args)
+
+
+def _validate_fromutc_inputs(f):
+    """
+    The CPython version of ``fromutc`` checks that the input is a ``datetime``
+    object and that ``self`` is attached as its ``tzinfo``.
+    """
+    @wraps(f)
+    def fromutc(self, dt):
+        if not isinstance(dt, datetime):
+            raise TypeError("fromutc() requires a datetime argument")
+        if dt.tzinfo is not self:
+            raise ValueError("dt.tzinfo is not self")
+
+        return f(self, dt)
+
+    return fromutc
+
+
+class _tzinfo(tzinfo):
+    """
+    Base class for all ``dateutil`` ``tzinfo`` objects.
+    """
+
+    def is_ambiguous(self, dt):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+
+        dt = dt.replace(tzinfo=self)
+
+        wall_0 = enfold(dt, fold=0)
+        wall_1 = enfold(dt, fold=1)
+
+        same_offset = wall_0.utcoffset() == wall_1.utcoffset()
+        same_dt = wall_0.replace(tzinfo=None) == wall_1.replace(tzinfo=None)
+
+        return same_dt and not same_offset
+
+    def _fold_status(self, dt_utc, dt_wall):
+        """
+        Determine the fold status of a "wall" datetime, given a representation
+        of the same datetime as a (naive) UTC datetime. This is calculated based
+        on the assumption that ``dt.utcoffset() - dt.dst()`` is constant for all
+        datetimes, and that this offset is the actual number of hours separating
+        ``dt_utc`` and ``dt_wall``.
+
+        :param dt_utc:
+            Representation of the datetime as UTC
+
+        :param dt_wall:
+            Representation of the datetime as "wall time". This parameter must
+            either have a `fold` attribute or have a fold-naive
+            :class:`datetime.tzinfo` attached, otherwise the calculation may
+            fail.
+        """
+        if self.is_ambiguous(dt_wall):
+            delta_wall = dt_wall - dt_utc
+            _fold = int(delta_wall == (dt_utc.utcoffset() - dt_utc.dst()))
+        else:
+            _fold = 0
+
+        return _fold
+
+    def _fold(self, dt):
+        return getattr(dt, 'fold', 0)
+
+    def _fromutc(self, dt):
+        """
+        Given a timezone-aware datetime in a given timezone, calculates a
+        timezone-aware datetime in a new timezone.
+
+        Since this is the one time that we *know* we have an unambiguous
+        datetime object, we take this opportunity to determine whether the
+        datetime is ambiguous and in a "fold" state (e.g. if it's the first
+        occurence, chronologically, of the ambiguous datetime).
+
+        :param dt:
+            A timezone-aware :class:`datetime.datetime` object.
+        """
+
+        # Re-implement the algorithm from Python's datetime.py
+        dtoff = dt.utcoffset()
+        if dtoff is None:
+            raise ValueError("fromutc() requires a non-None utcoffset() "
+                             "result")
+
+        # The original datetime.py code assumes that `dst()` defaults to
+        # zero during ambiguous times. PEP 495 inverts this presumption, so
+        # for pre-PEP 495 versions of python, we need to tweak the algorithm.
+        dtdst = dt.dst()
+        if dtdst is None:
+            raise ValueError("fromutc() requires a non-None dst() result")
+        delta = dtoff - dtdst
+
+        dt += delta
+        # Set fold=1 so we can default to being in the fold for
+        # ambiguous dates.
+        dtdst = enfold(dt, fold=1).dst()
+        if dtdst is None:
+            raise ValueError("fromutc(): dt.dst gave inconsistent "
+                             "results; cannot convert")
+        return dt + dtdst
+
+    @_validate_fromutc_inputs
+    def fromutc(self, dt):
+        """
+        Given a timezone-aware datetime in a given timezone, calculates a
+        timezone-aware datetime in a new timezone.
+
+        Since this is the one time that we *know* we have an unambiguous
+        datetime object, we take this opportunity to determine whether the
+        datetime is ambiguous and in a "fold" state (e.g. if it's the first
+        occurance, chronologically, of the ambiguous datetime).
+
+        :param dt:
+            A timezone-aware :class:`datetime.datetime` object.
+        """
+        dt_wall = self._fromutc(dt)
+
+        # Calculate the fold status given the two datetimes.
+        _fold = self._fold_status(dt, dt_wall)
+
+        # Set the default fold value for ambiguous dates
+        return enfold(dt_wall, fold=_fold)
+
+
+class tzrangebase(_tzinfo):
+    """
+    This is an abstract base class for time zones represented by an annual
+    transition into and out of DST. Child classes should implement the following
+    methods:
+
+        * ``__init__(self, *args, **kwargs)``
+        * ``transitions(self, year)`` - this is expected to return a tuple of
+          datetimes representing the DST on and off transitions in standard
+          time.
+
+    A fully initialized ``tzrangebase`` subclass should also provide the
+    following attributes:
+        * ``hasdst``: Boolean whether or not the zone uses DST.
+        * ``_dst_offset`` / ``_std_offset``: :class:`datetime.timedelta` objects
+          representing the respective UTC offsets.
+        * ``_dst_abbr`` / ``_std_abbr``: Strings representing the timezone short
+          abbreviations in DST and STD, respectively.
+        * ``_hasdst``: Whether or not the zone has DST.
+
+    .. versionadded:: 2.6.0
+    """
+    def __init__(self):
+        raise NotImplementedError('tzrangebase is an abstract base class')
+
+    def utcoffset(self, dt):
+        isdst = self._isdst(dt)
+
+        if isdst is None:
+            return None
+        elif isdst:
+            return self._dst_offset
+        else:
+            return self._std_offset
+
+    def dst(self, dt):
+        isdst = self._isdst(dt)
+
+        if isdst is None:
+            return None
+        elif isdst:
+            return self._dst_base_offset
+        else:
+            return ZERO
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        if self._isdst(dt):
+            return self._dst_abbr
+        else:
+            return self._std_abbr
+
+    def fromutc(self, dt):
+        """ Given a datetime in UTC, return local time """
+        if not isinstance(dt, datetime):
+            raise TypeError("fromutc() requires a datetime argument")
+
+        if dt.tzinfo is not self:
+            raise ValueError("dt.tzinfo is not self")
+
+        # Get transitions - if there are none, fixed offset
+        transitions = self.transitions(dt.year)
+        if transitions is None:
+            return dt + self.utcoffset(dt)
+
+        # Get the transition times in UTC
+        dston, dstoff = transitions
+
+        dston -= self._std_offset
+        dstoff -= self._std_offset
+
+        utc_transitions = (dston, dstoff)
+        dt_utc = dt.replace(tzinfo=None)
+
+        isdst = self._naive_isdst(dt_utc, utc_transitions)
+
+        if isdst:
+            dt_wall = dt + self._dst_offset
+        else:
+            dt_wall = dt + self._std_offset
+
+        _fold = int(not isdst and self.is_ambiguous(dt_wall))
+
+        return enfold(dt_wall, fold=_fold)
+
+    def is_ambiguous(self, dt):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+        if not self.hasdst:
+            return False
+
+        start, end = self.transitions(dt.year)
+
+        dt = dt.replace(tzinfo=None)
+        return (end <= dt < end + self._dst_base_offset)
+
+    def _isdst(self, dt):
+        if not self.hasdst:
+            return False
+        elif dt is None:
+            return None
+
+        transitions = self.transitions(dt.year)
+
+        if transitions is None:
+            return False
+
+        dt = dt.replace(tzinfo=None)
+
+        isdst = self._naive_isdst(dt, transitions)
+
+        # Handle ambiguous dates
+        if not isdst and self.is_ambiguous(dt):
+            return not self._fold(dt)
+        else:
+            return isdst
+
+    def _naive_isdst(self, dt, transitions):
+        dston, dstoff = transitions
+
+        dt = dt.replace(tzinfo=None)
+
+        if dston < dstoff:
+            isdst = dston <= dt < dstoff
+        else:
+            isdst = not dstoff <= dt < dston
+
+        return isdst
+
+    @property
+    def _dst_base_offset(self):
+        return self._dst_offset - self._std_offset
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __repr__(self):
+        return "%s(...)" % self.__class__.__name__
+
+    __reduce__ = object.__reduce__
+
+
+def _total_seconds(td):
+    # Python 2.6 doesn't have a total_seconds() method on timedelta objects
+    return ((td.seconds + td.days * 86400) * 1000000 +
+            td.microseconds) // 1000000
+
+
+_total_seconds = getattr(timedelta, 'total_seconds', _total_seconds)
diff --git a/python/dateutil/tz/tz.py b/python/dateutil/tz/tz.py
new file mode 100644
index 0000000..9468282
--- /dev/null
+++ b/python/dateutil/tz/tz.py
@@ -0,0 +1,1511 @@
+# -*- coding: utf-8 -*-
+"""
+This module offers timezone implementations subclassing the abstract
+:py:`datetime.tzinfo` type. There are classes to handle tzfile format files
+(usually are in :file:`/etc/localtime`, :file:`/usr/share/zoneinfo`, etc), TZ
+environment string (in all known formats), given ranges (with help from
+relative deltas), local machine timezone, fixed offset timezone, and UTC
+timezone.
+"""
+import datetime
+import struct
+import time
+import sys
+import os
+import bisect
+
+from six import string_types
+from ._common import tzname_in_python2, _tzinfo, _total_seconds
+from ._common import tzrangebase, enfold
+from ._common import _validate_fromutc_inputs
+
+try:
+    from .win import tzwin, tzwinlocal
+except ImportError:
+    tzwin = tzwinlocal = None
+
+ZERO = datetime.timedelta(0)
+EPOCH = datetime.datetime.utcfromtimestamp(0)
+EPOCHORDINAL = EPOCH.toordinal()
+
+
+class tzutc(datetime.tzinfo):
+    """
+    This is a tzinfo object that represents the UTC time zone.
+    """
+    def utcoffset(self, dt):
+        return ZERO
+
+    def dst(self, dt):
+        return ZERO
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        return "UTC"
+
+    def is_ambiguous(self, dt):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+        return False
+
+    @_validate_fromutc_inputs
+    def fromutc(self, dt):
+        """
+        Fast track version of fromutc() returns the original ``dt`` object for
+        any valid :py:class:`datetime.datetime` object.
+        """
+        return dt
+
+    def __eq__(self, other):
+        if not isinstance(other, (tzutc, tzoffset)):
+            return NotImplemented
+
+        return (isinstance(other, tzutc) or
+                (isinstance(other, tzoffset) and other._offset == ZERO))
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __repr__(self):
+        return "%s()" % self.__class__.__name__
+
+    __reduce__ = object.__reduce__
+
+
+class tzoffset(datetime.tzinfo):
+    """
+    A simple class for representing a fixed offset from UTC.
+
+    :param name:
+        The timezone name, to be returned when ``tzname()`` is called.
+
+    :param offset:
+        The time zone offset in seconds, or (since version 2.6.0, represented
+        as a :py:class:`datetime.timedelta` object.
+    """
+    def __init__(self, name, offset):
+        self._name = name
+
+        try:
+            # Allow a timedelta
+            offset = _total_seconds(offset)
+        except (TypeError, AttributeError):
+            pass
+        self._offset = datetime.timedelta(seconds=offset)
+
+    def utcoffset(self, dt):
+        return self._offset
+
+    def dst(self, dt):
+        return ZERO
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        return self._name
+
+    @_validate_fromutc_inputs
+    def fromutc(self, dt):
+        return dt + self._offset
+
+    def is_ambiguous(self, dt):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+        return False
+
+    def __eq__(self, other):
+        if not isinstance(other, tzoffset):
+            return NotImplemented
+
+        return self._offset == other._offset
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __repr__(self):
+        return "%s(%s, %s)" % (self.__class__.__name__,
+                               repr(self._name),
+                               int(_total_seconds(self._offset)))
+
+    __reduce__ = object.__reduce__
+
+
+class tzlocal(_tzinfo):
+    """
+    A :class:`tzinfo` subclass built around the ``time`` timezone functions.
+    """
+    def __init__(self):
+        super(tzlocal, self).__init__()
+
+        self._std_offset = datetime.timedelta(seconds=-time.timezone)
+        if time.daylight:
+            self._dst_offset = datetime.timedelta(seconds=-time.altzone)
+        else:
+            self._dst_offset = self._std_offset
+
+        self._dst_saved = self._dst_offset - self._std_offset
+        self._hasdst = bool(self._dst_saved)
+
+    def utcoffset(self, dt):
+        if dt is None and self._hasdst:
+            return None
+
+        if self._isdst(dt):
+            return self._dst_offset
+        else:
+            return self._std_offset
+
+    def dst(self, dt):
+        if dt is None and self._hasdst:
+            return None
+
+        if self._isdst(dt):
+            return self._dst_offset - self._std_offset
+        else:
+            return ZERO
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        return time.tzname[self._isdst(dt)]
+
+    def is_ambiguous(self, dt):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+        naive_dst = self._naive_is_dst(dt)
+        return (not naive_dst and
+                (naive_dst != self._naive_is_dst(dt - self._dst_saved)))
+
+    def _naive_is_dst(self, dt):
+        timestamp = _datetime_to_timestamp(dt)
+        return time.localtime(timestamp + time.timezone).tm_isdst
+
+    def _isdst(self, dt, fold_naive=True):
+        # We can't use mktime here. It is unstable when deciding if
+        # the hour near to a change is DST or not.
+        #
+        # timestamp = time.mktime((dt.year, dt.month, dt.day, dt.hour,
+        #                         dt.minute, dt.second, dt.weekday(), 0, -1))
+        # return time.localtime(timestamp).tm_isdst
+        #
+        # The code above yields the following result:
+        #
+        # >>> import tz, datetime
+        # >>> t = tz.tzlocal()
+        # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
+        # 'BRDT'
+        # >>> datetime.datetime(2003,2,16,0,tzinfo=t).tzname()
+        # 'BRST'
+        # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
+        # 'BRST'
+        # >>> datetime.datetime(2003,2,15,22,tzinfo=t).tzname()
+        # 'BRDT'
+        # >>> datetime.datetime(2003,2,15,23,tzinfo=t).tzname()
+        # 'BRDT'
+        #
+        # Here is a more stable implementation:
+        #
+        if not self._hasdst:
+            return False
+
+        # Check for ambiguous times:
+        dstval = self._naive_is_dst(dt)
+        fold = getattr(dt, 'fold', None)
+
+        if self.is_ambiguous(dt):
+            if fold is not None:
+                return not self._fold(dt)
+            else:
+                return True
+
+        return dstval
+
+    def __eq__(self, other):
+        if not isinstance(other, tzlocal):
+            return NotImplemented
+
+        return (self._std_offset == other._std_offset and
+                self._dst_offset == other._dst_offset)
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __repr__(self):
+        return "%s()" % self.__class__.__name__
+
+    __reduce__ = object.__reduce__
+
+
+class _ttinfo(object):
+    __slots__ = ["offset", "delta", "isdst", "abbr",
+                 "isstd", "isgmt", "dstoffset"]
+
+    def __init__(self):
+        for attr in self.__slots__:
+            setattr(self, attr, None)
+
+    def __repr__(self):
+        l = []
+        for attr in self.__slots__:
+            value = getattr(self, attr)
+            if value is not None:
+                l.append("%s=%s" % (attr, repr(value)))
+        return "%s(%s)" % (self.__class__.__name__, ", ".join(l))
+
+    def __eq__(self, other):
+        if not isinstance(other, _ttinfo):
+            return NotImplemented
+
+        return (self.offset == other.offset and
+                self.delta == other.delta and
+                self.isdst == other.isdst and
+                self.abbr == other.abbr and
+                self.isstd == other.isstd and
+                self.isgmt == other.isgmt and
+                self.dstoffset == other.dstoffset)
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __getstate__(self):
+        state = {}
+        for name in self.__slots__:
+            state[name] = getattr(self, name, None)
+        return state
+
+    def __setstate__(self, state):
+        for name in self.__slots__:
+            if name in state:
+                setattr(self, name, state[name])
+
+
+class _tzfile(object):
+    """
+    Lightweight class for holding the relevant transition and time zone
+    information read from binary tzfiles.
+    """
+    attrs = ['trans_list', 'trans_list_utc', 'trans_idx', 'ttinfo_list',
+             'ttinfo_std', 'ttinfo_dst', 'ttinfo_before', 'ttinfo_first']
+
+    def __init__(self, **kwargs):
+        for attr in self.attrs:
+            setattr(self, attr, kwargs.get(attr, None))
+
+
+class tzfile(_tzinfo):
+    """
+    This is a ``tzinfo`` subclass thant allows one to use the ``tzfile(5)``
+    format timezone files to extract current and historical zone information.
+
+    :param fileobj:
+        This can be an opened file stream or a file name that the time zone
+        information can be read from.
+
+    :param filename:
+        This is an optional parameter specifying the source of the time zone
+        information in the event that ``fileobj`` is a file object. If omitted
+        and ``fileobj`` is a file stream, this parameter will be set either to
+        ``fileobj``'s ``name`` attribute or to ``repr(fileobj)``.
+
+    See `Sources for Time Zone and Daylight Saving Time Data
+    <http://www.twinsun.com/tz/tz-link.htm>`_ for more information. Time zone
+    files can be compiled from the `IANA Time Zone database files
+    <https://www.iana.org/time-zones>`_ with the `zic time zone compiler
+    <https://www.freebsd.org/cgi/man.cgi?query=zic&sektion=8>`_
+    """
+
+    def __init__(self, fileobj, filename=None):
+        super(tzfile, self).__init__()
+
+        file_opened_here = False
+        if isinstance(fileobj, string_types):
+            self._filename = fileobj
+            fileobj = open(fileobj, 'rb')
+            file_opened_here = True
+        elif filename is not None:
+            self._filename = filename
+        elif hasattr(fileobj, "name"):
+            self._filename = fileobj.name
+        else:
+            self._filename = repr(fileobj)
+
+        if fileobj is not None:
+            if not file_opened_here:
+                fileobj = _ContextWrapper(fileobj)
+
+            with fileobj as file_stream:
+                tzobj = self._read_tzfile(file_stream)
+
+            self._set_tzdata(tzobj)
+
+    def _set_tzdata(self, tzobj):
+        """ Set the time zone data of this object from a _tzfile object """
+        # Copy the relevant attributes over as private attributes
+        for attr in _tzfile.attrs:
+            setattr(self, '_' + attr, getattr(tzobj, attr))
+
+    def _read_tzfile(self, fileobj):
+        out = _tzfile()
+
+        # From tzfile(5):
+        #
+        # The time zone information files used by tzset(3)
+        # begin with the magic characters "TZif" to identify
+        # them as time zone information files, followed by
+        # sixteen bytes reserved for future use, followed by
+        # six four-byte values of type long, written in a
+        # ``standard'' byte order (the high-order  byte
+        # of the value is written first).
+        if fileobj.read(4).decode() != "TZif":
+            raise ValueError("magic not found")
+
+        fileobj.read(16)
+
+        (
+            # The number of UTC/local indicators stored in the file.
+            ttisgmtcnt,
+
+            # The number of standard/wall indicators stored in the file.
+            ttisstdcnt,
+
+            # The number of leap seconds for which data is
+            # stored in the file.
+            leapcnt,
+
+            # The number of "transition times" for which data
+            # is stored in the file.
+            timecnt,
+
+            # The number of "local time types" for which data
+            # is stored in the file (must not be zero).
+            typecnt,
+
+            # The  number  of  characters  of "time zone
+            # abbreviation strings" stored in the file.
+            charcnt,
+
+        ) = struct.unpack(">6l", fileobj.read(24))
+
+        # The above header is followed by tzh_timecnt four-byte
+        # values  of  type long,  sorted  in ascending order.
+        # These values are written in ``standard'' byte order.
+        # Each is used as a transition time (as  returned  by
+        # time(2)) at which the rules for computing local time
+        # change.
+
+        if timecnt:
+            out.trans_list_utc = list(struct.unpack(">%dl" % timecnt,
+                                                    fileobj.read(timecnt*4)))
+        else:
+            out.trans_list_utc = []
+
+        # Next come tzh_timecnt one-byte values of type unsigned
+        # char; each one tells which of the different types of
+        # ``local time'' types described in the file is associated
+        # with the same-indexed transition time. These values
+        # serve as indices into an array of ttinfo structures that
+        # appears next in the file.
+
+        if timecnt:
+            out.trans_idx = struct.unpack(">%dB" % timecnt,
+                                            fileobj.read(timecnt))
+        else:
+            out.trans_idx = []
+
+        # Each ttinfo structure is written as a four-byte value
+        # for tt_gmtoff  of  type long,  in  a  standard  byte
+        # order, followed  by a one-byte value for tt_isdst
+        # and a one-byte  value  for  tt_abbrind.   In  each
+        # structure, tt_gmtoff  gives  the  number  of
+        # seconds to be added to UTC, tt_isdst tells whether
+        # tm_isdst should be set by  localtime(3),  and
+        # tt_abbrind serves  as an index into the array of
+        # time zone abbreviation characters that follow the
+        # ttinfo structure(s) in the file.
+
+        ttinfo = []
+
+        for i in range(typecnt):
+            ttinfo.append(struct.unpack(">lbb", fileobj.read(6)))
+
+        abbr = fileobj.read(charcnt).decode()
+
+        # Then there are tzh_leapcnt pairs of four-byte
+        # values, written in  standard byte  order;  the
+        # first  value  of  each pair gives the time (as
+        # returned by time(2)) at which a leap second
+        # occurs;  the  second  gives the  total  number of
+        # leap seconds to be applied after the given time.
+        # The pairs of values are sorted in ascending order
+        # by time.
+
+        # Not used, for now (but seek for correct file position)
+        if leapcnt:
+            fileobj.seek(leapcnt * 8, os.SEEK_CUR)
+
+        # Then there are tzh_ttisstdcnt standard/wall
+        # indicators, each stored as a one-byte value;
+        # they tell whether the transition times associated
+        # with local time types were specified as standard
+        # time or wall clock time, and are used when
+        # a time zone file is used in handling POSIX-style
+        # time zone environment variables.
+
+        if ttisstdcnt:
+            isstd = struct.unpack(">%db" % ttisstdcnt,
+                                  fileobj.read(ttisstdcnt))
+
+        # Finally, there are tzh_ttisgmtcnt UTC/local
+        # indicators, each stored as a one-byte value;
+        # they tell whether the transition times associated
+        # with local time types were specified as UTC or
+        # local time, and are used when a time zone file
+        # is used in handling POSIX-style time zone envi-
+        # ronment variables.
+
+        if ttisgmtcnt:
+            isgmt = struct.unpack(">%db" % ttisgmtcnt,
+                                  fileobj.read(ttisgmtcnt))
+
+        # Build ttinfo list
+        out.ttinfo_list = []
+        for i in range(typecnt):
+            gmtoff, isdst, abbrind = ttinfo[i]
+            # Round to full-minutes if that's not the case. Python's
+            # datetime doesn't accept sub-minute timezones. Check
+            # http://python.org/sf/1447945 for some information.
+            gmtoff = 60 * ((gmtoff + 30) // 60)
+            tti = _ttinfo()
+            tti.offset = gmtoff
+            tti.dstoffset = datetime.timedelta(0)
+            tti.delta = datetime.timedelta(seconds=gmtoff)
+            tti.isdst = isdst
+            tti.abbr = abbr[abbrind:abbr.find('\x00', abbrind)]
+            tti.isstd = (ttisstdcnt > i and isstd[i] != 0)
+            tti.isgmt = (ttisgmtcnt > i and isgmt[i] != 0)
+            out.ttinfo_list.append(tti)
+
+        # Replace ttinfo indexes for ttinfo objects.
+        out.trans_idx = [out.ttinfo_list[idx] for idx in out.trans_idx]
+
+        # Set standard, dst, and before ttinfos. before will be
+        # used when a given time is before any transitions,
+        # and will be set to the first non-dst ttinfo, or to
+        # the first dst, if all of them are dst.
+        out.ttinfo_std = None
+        out.ttinfo_dst = None
+        out.ttinfo_before = None
+        if out.ttinfo_list:
+            if not out.trans_list_utc:
+                out.ttinfo_std = out.ttinfo_first = out.ttinfo_list[0]
+            else:
+                for i in range(timecnt-1, -1, -1):
+                    tti = out.trans_idx[i]
+                    if not out.ttinfo_std and not tti.isdst:
+                        out.ttinfo_std = tti
+                    elif not out.ttinfo_dst and tti.isdst:
+                        out.ttinfo_dst = tti
+
+                    if out.ttinfo_std and out.ttinfo_dst:
+                        break
+                else:
+                    if out.ttinfo_dst and not out.ttinfo_std:
+                        out.ttinfo_std = out.ttinfo_dst
+
+                for tti in out.ttinfo_list:
+                    if not tti.isdst:
+                        out.ttinfo_before = tti
+                        break
+                else:
+                    out.ttinfo_before = out.ttinfo_list[0]
+
+        # Now fix transition times to become relative to wall time.
+        #
+        # I'm not sure about this. In my tests, the tz source file
+        # is setup to wall time, and in the binary file isstd and
+        # isgmt are off, so it should be in wall time. OTOH, it's
+        # always in gmt time. Let me know if you have comments
+        # about this.
+        laststdoffset = None
+        out.trans_list = []
+        for i, tti in enumerate(out.trans_idx):
+            if not tti.isdst:
+                offset = tti.offset
+                laststdoffset = offset
+            else:
+                if laststdoffset is not None:
+                    # Store the DST offset as well and update it in the list
+                    tti.dstoffset = tti.offset - laststdoffset
+                    out.trans_idx[i] = tti
+
+                offset = laststdoffset or 0
+
+            out.trans_list.append(out.trans_list_utc[i] + offset)
+
+        # In case we missed any DST offsets on the way in for some reason, make
+        # a second pass over the list, looking for the /next/ DST offset.
+        laststdoffset = None
+        for i in reversed(range(len(out.trans_idx))):
+            tti = out.trans_idx[i]
+            if tti.isdst:
+                if not (tti.dstoffset or laststdoffset is None):
+                    tti.dstoffset = tti.offset - laststdoffset
+            else:
+                laststdoffset = tti.offset
+
+            if not isinstance(tti.dstoffset, datetime.timedelta):
+                tti.dstoffset = datetime.timedelta(seconds=tti.dstoffset)
+
+            out.trans_idx[i] = tti
+
+        out.trans_idx = tuple(out.trans_idx)
+        out.trans_list = tuple(out.trans_list)
+        out.trans_list_utc = tuple(out.trans_list_utc)
+
+        return out
+
+    def _find_last_transition(self, dt, in_utc=False):
+        # If there's no list, there are no transitions to find
+        if not self._trans_list:
+            return None
+
+        timestamp = _datetime_to_timestamp(dt)
+
+        # Find where the timestamp fits in the transition list - if the
+        # timestamp is a transition time, it's part of the "after" period.
+        trans_list = self._trans_list_utc if in_utc else self._trans_list
+        idx = bisect.bisect_right(trans_list, timestamp)
+
+        # We want to know when the previous transition was, so subtract off 1
+        return idx - 1        
+
+    def _get_ttinfo(self, idx):
+        # For no list or after the last transition, default to _ttinfo_std
+        if idx is None or (idx + 1) >= len(self._trans_list):
+            return self._ttinfo_std
+
+        # If there is a list and the time is before it, return _ttinfo_before
+        if idx < 0:
+            return self._ttinfo_before
+
+        return self._trans_idx[idx]
+
+    def _find_ttinfo(self, dt):
+        idx = self._resolve_ambiguous_time(dt)
+
+        return self._get_ttinfo(idx)
+
+    def fromutc(self, dt):
+        """
+        The ``tzfile`` implementation of :py:func:`datetime.tzinfo.fromutc`.
+
+        :param dt:
+            A :py:class:`datetime.datetime` object.
+
+        :raises TypeError:
+            Raised if ``dt`` is not a :py:class:`datetime.datetime` object.
+
+        :raises ValueError:
+            Raised if this is called with a ``dt`` which does not have this
+            ``tzinfo`` attached.
+
+        :return:
+            Returns a :py:class:`datetime.datetime` object representing the
+            wall time in ``self``'s time zone.
+        """
+        # These isinstance checks are in datetime.tzinfo, so we'll preserve
+        # them, even if we don't care about duck typing.
+        if not isinstance(dt, datetime.datetime):
+            raise TypeError("fromutc() requires a datetime argument")
+
+        if dt.tzinfo is not self:
+            raise ValueError("dt.tzinfo is not self")
+
+        # First treat UTC as wall time and get the transition we're in.
+        idx = self._find_last_transition(dt, in_utc=True)
+        tti = self._get_ttinfo(idx)
+
+        dt_out = dt + datetime.timedelta(seconds=tti.offset)
+
+        fold = self.is_ambiguous(dt_out, idx=idx)
+
+        return enfold(dt_out, fold=int(fold))
+
+    def is_ambiguous(self, dt, idx=None):
+        """
+        Whether or not the "wall time" of a given datetime is ambiguous in this
+        zone.
+
+        :param dt:
+            A :py:class:`datetime.datetime`, naive or time zone aware.
+
+
+        :return:
+            Returns ``True`` if ambiguous, ``False`` otherwise.
+
+        .. versionadded:: 2.6.0
+        """
+        if idx is None:
+            idx = self._find_last_transition(dt)
+
+        # Calculate the difference in offsets from current to previous
+        timestamp = _datetime_to_timestamp(dt)
+        tti = self._get_ttinfo(idx)
+
+        if idx is None or idx <= 0:
+            return False
+
+        od = self._get_ttinfo(idx - 1).offset - tti.offset
+        tt = self._trans_list[idx]          # Transition time
+
+        return timestamp < tt + od
+
+    def _resolve_ambiguous_time(self, dt):
+        idx = self._find_last_transition(dt)
+
+        # If we have no transitions, return the index
+        _fold = self._fold(dt)
+        if idx is None or idx == 0:
+            return idx
+
+        # If it's ambiguous and we're in a fold, shift to a different index.
+        idx_offset = int(not _fold and self.is_ambiguous(dt, idx))
+
+        return idx - idx_offset
+
+    def utcoffset(self, dt):
+        if dt is None:
+            return None
+
+        if not self._ttinfo_std:
+            return ZERO
+
+        return self._find_ttinfo(dt).delta
+
+    def dst(self, dt):
+        if dt is None:
+            return None
+
+        if not self._ttinfo_dst:
+            return ZERO
+
+        tti = self._find_ttinfo(dt)
+
+        if not tti.isdst:
+            return ZERO
+
+        # The documentation says that utcoffset()-dst() must
+        # be constant for every dt.
+        return tti.dstoffset
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        if not self._ttinfo_std or dt is None:
+            return None
+        return self._find_ttinfo(dt).abbr
+
+    def __eq__(self, other):
+        if not isinstance(other, tzfile):
+            return NotImplemented
+        return (self._trans_list == other._trans_list and
+                self._trans_idx == other._trans_idx and
+                self._ttinfo_list == other._ttinfo_list)
+
+    __hash__ = None
+
+    def __ne__(self, other):
+        return not (self == other)
+
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, repr(self._filename))
+
+    def __reduce__(self):
+        return self.__reduce_ex__(None)
+
+    def __reduce_ex__(self, protocol):
+        return (self.__class__, (None, self._filename), self.__dict__)
+
+
+class tzrange(tzrangebase):
+    """
+    The ``tzrange`` object is a time zone specified by a set of offsets and
+    abbreviations, equivalent to the way the ``TZ`` variable can be specified
+    in POSIX-like systems, but using Python delta objects to specify DST
+    start, end and offsets.
+
+    :param stdabbr:
+        The abbreviation for standard time (e.g. ``'EST'``).
+
+    :param stdoffset:
+        An integer or :class:`datetime.timedelta` object or equivalent
+        specifying the base offset from UTC.
+
+        If unspecified, +00:00 is used.
+
+    :param dstabbr:
+        The abbreviation for DST / "Summer" time (e.g. ``'EDT'``).
+
+        If specified, with no other DST information, DST is assumed to occur
+        and the default behavior or ``dstoffset``, ``start`` and ``end`` is
+        used. If unspecified and no other DST information is specified, it
+        is assumed that this zone has no DST.
+
+        If this is unspecified and other DST information is *is* specified,
+        DST occurs in the zone but the time zone abbreviation is left
+        unchanged.
+
+    :param dstoffset:
+        A an integer or :class:`datetime.timedelta` object or equivalent
+        specifying the UTC offset during DST. If unspecified and any other DST
+        information is specified, it is assumed to be the STD offset +1 hour.
+
+    :param start:
+        A :class:`relativedelta.relativedelta` object or equivalent specifying
+        the time and time of year that daylight savings time starts. To specify,
+        for example, that DST starts at 2AM on the 2nd Sunday in March, pass:
+
+            ``relativedelta(hours=2, month=3, day=1, weekday=SU(+2))``
+
+        If unspecified and any other DST information is specified, the default
+        value is 2 AM on the first Sunday in April.
+
+    :param end:
+        A :class:`relativedelta.relativedelta` object or equivalent representing
+        the time and time of year that daylight savings time ends, with the
+        same specification method as in ``start``. One note is that this should
+        point to the first time in the *standard* zone, so if a transition
+        occurs at 2AM in the DST zone and the clocks are set back 1 hour to 1AM,
+        set the `hours` parameter to +1.
+
+
+    **Examples:**
+
+    .. testsetup:: tzrange
+
+        from dateutil.tz import tzrange, tzstr
+
+    .. doctest:: tzrange
+
+        >>> tzstr('EST5EDT') == tzrange("EST", -18000, "EDT")
+        True
+
+        >>> from dateutil.relativedelta import *
+        >>> range1 = tzrange("EST", -18000, "EDT")
+        >>> range2 = tzrange("EST", -18000, "EDT", -14400,
+        ...                  relativedelta(hours=+2, month=4, day=1,
+        ...                                weekday=SU(+1)),
+        ...                  relativedelta(hours=+1, month=10, day=31,
+        ...                                weekday=SU(-1)))
+        >>> tzstr('EST5EDT') == range1 == range2
+        True
+
+    """
+    def __init__(self, stdabbr, stdoffset=None,
+                 dstabbr=None, dstoffset=None,
+                 start=None, end=None):
+
+        global relativedelta
+        from dateutil import relativedelta
+
+        self._std_abbr = stdabbr
+        self._dst_abbr = dstabbr
+
+        try:
+            stdoffset = _total_seconds(stdoffset)
+        except (TypeError, AttributeError):
+            pass
+
+        try:
+            dstoffset = _total_seconds(dstoffset)
+        except (TypeError, AttributeError):
+            pass
+
+        if stdoffset is not None:
+            self._std_offset = datetime.timedelta(seconds=stdoffset)
+        else:
+            self._std_offset = ZERO
+
+        if dstoffset is not None:
+            self._dst_offset = datetime.timedelta(seconds=dstoffset)
+        elif dstabbr and stdoffset is not None:
+            self._dst_offset = self._std_offset + datetime.timedelta(hours=+1)
+        else:
+            self._dst_offset = ZERO
+
+        if dstabbr and start is None:
+            self._start_delta = relativedelta.relativedelta(
+                hours=+2, month=4, day=1, weekday=relativedelta.SU(+1))
+        else:
+            self._start_delta = start
+
+        if dstabbr and end is None:
+            self._end_delta = relativedelta.relativedelta(
+                hours=+1, month=10, day=31, weekday=relativedelta.SU(-1))
+        else:
+            self._end_delta = end
+
+        self._dst_base_offset_ = self._dst_offset - self._std_offset
+        self.hasdst = bool(self._start_delta)
+
+    def transitions(self, year):
+        """
+        For a given year, get the DST on and off transition times, expressed
+        always on the standard time side. For zones with no transitions, this
+        function returns ``None``.
+
+        :param year:
+            The year whose transitions you would like to query.
+
+        :return:
+            Returns a :class:`tuple` of :class:`datetime.datetime` objects,
+            ``(dston, dstoff)`` for zones with an annual DST transition, or
+            ``None`` for fixed offset zones.
+        """
+        if not self.hasdst:
+            return None
+
+        base_year = datetime.datetime(year, 1, 1)
+
+        start = base_year + self._start_delta
+        end = base_year + self._end_delta
+
+        return (start, end)
+
+    def __eq__(self, other):
+        if not isinstance(other, tzrange):
+            return NotImplemented
+
+        return (self._std_abbr == other._std_abbr and
+                self._dst_abbr == other._dst_abbr and
+                self._std_offset == other._std_offset and
+                self._dst_offset == other._dst_offset and
+                self._start_delta == other._start_delta and
+                self._end_delta == other._end_delta)
+
+    @property
+    def _dst_base_offset(self):
+        return self._dst_base_offset_
+
+
+class tzstr(tzrange):
+    """
+    ``tzstr`` objects are time zone objects specified by a time-zone string as
+    it would be passed to a ``TZ`` variable on POSIX-style systems (see
+    the `GNU C Library: TZ Variable`_ for more details).
+
+    There is one notable exception, which is that POSIX-style time zones use an
+    inverted offset format, so normally ``GMT+3`` would be parsed as an offset
+    3 hours *behind* GMT. The ``tzstr`` time zone object will parse this as an
+    offset 3 hours *ahead* of GMT. If you would like to maintain the POSIX
+    behavior, pass a ``True`` value to ``posix_offset``.
+
+    The :class:`tzrange` object provides the same functionality, but is
+    specified using :class:`relativedelta.relativedelta` objects. rather than
+    strings.
+
+    :param s:
+        A time zone string in ``TZ`` variable format. This can be a
+        :class:`bytes` (2.x: :class:`str`), :class:`str` (2.x: :class:`unicode`)
+        or a stream emitting unicode characters (e.g. :class:`StringIO`).
+
+    :param posix_offset:
+        Optional. If set to ``True``, interpret strings such as ``GMT+3`` or
+        ``UTC+3`` as being 3 hours *behind* UTC rather than ahead, per the
+        POSIX standard.
+
+    .. _`GNU C Library: TZ Variable`:
+        https://www.gnu.org/software/libc/manual/html_node/TZ-Variable.html
+    """
+    def __init__(self, s, posix_offset=False):
+        global parser
+        from dateutil import parser
+
+        self._s = s
+
+        res = parser._parsetz(s)
+        if res is None:
+            raise ValueError("unknown string format")
+
+        # Here we break the compatibility with the TZ variable handling.
+        # GMT-3 actually *means* the timezone -3.
+        if res.stdabbr in ("GMT", "UTC") and not posix_offset:
+            res.stdoffset *= -1
+
+        # We must initialize it first, since _delta() needs
+        # _std_offset and _dst_offset set. Use False in start/end
+        # to avoid building it two times.
+        tzrange.__init__(self, res.stdabbr, res.stdoffset,
+                         res.dstabbr, res.dstoffset,
+                         start=False, end=False)
+
+        if not res.dstabbr:
+            self._start_delta = None
+            self._end_delta = None
+        else:
+            self._start_delta = self._delta(res.start)
+            if self._start_delta:
+                self._end_delta = self._delta(res.end, isend=1)
+
+        self.hasdst = bool(self._start_delta)
+
+    def _delta(self, x, isend=0):
+        from dateutil import relativedelta
+        kwargs = {}
+        if x.month is not None:
+            kwargs["month"] = x.month
+            if x.weekday is not None:
+                kwargs["weekday"] = relativedelta.weekday(x.weekday, x.week)
+                if x.week > 0:
+                    kwargs["day"] = 1
+                else:
+                    kwargs["day"] = 31
+            elif x.day:
+                kwargs["day"] = x.day
+        elif x.yday is not None:
+            kwargs["yearday"] = x.yday
+        elif x.jyday is not None:
+            kwargs["nlyearday"] = x.jyday
+        if not kwargs:
+            # Default is to start on first sunday of april, and end
+            # on last sunday of october.
+            if not isend:
+                kwargs["month"] = 4
+                kwargs["day"] = 1
+                kwargs["weekday"] = relativedelta.SU(+1)
+            else:
+                kwargs["month"] = 10
+                kwargs["day"] = 31
+                kwargs["weekday"] = relativedelta.SU(-1)
+        if x.time is not None:
+            kwargs["seconds"] = x.time
+        else:
+            # Default is 2AM.
+            kwargs["seconds"] = 7200
+        if isend:
+            # Convert to standard time, to follow the documented way
+            # of working with the extra hour. See the documentation
+            # of the tzinfo class.
+            delta = self._dst_offset - self._std_offset
+            kwargs["seconds"] -= delta.seconds + delta.days * 86400
+        return relativedelta.relativedelta(**kwargs)
+
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, repr(self._s))
+
+
+class _tzicalvtzcomp(object):
+    def __init__(self, tzoffsetfrom, tzoffsetto, isdst,
+                 tzname=None, rrule=None):
+        self.tzoffsetfrom = datetime.timedelta(seconds=tzoffsetfrom)
+        self.tzoffsetto = datetime.timedelta(seconds=tzoffsetto)
+        self.tzoffsetdiff = self.tzoffsetto - self.tzoffsetfrom
+        self.isdst = isdst
+        self.tzname = tzname
+        self.rrule = rrule
+
+
+class _tzicalvtz(_tzinfo):
+    def __init__(self, tzid, comps=[]):
+        super(_tzicalvtz, self).__init__()
+
+        self._tzid = tzid
+        self._comps = comps
+        self._cachedate = []
+        self._cachecomp = []
+
+    def _find_comp(self, dt):
+        if len(self._comps) == 1:
+            return self._comps[0]
+
+        dt = dt.replace(tzinfo=None)
+
+        try:
+            return self._cachecomp[self._cachedate.index((dt, self._fold(dt)))]
+        except ValueError:
+            pass
+
+        lastcompdt = None
+        lastcomp = None
+
+        for comp in self._comps:
+            compdt = self._find_compdt(comp, dt)
+
+            if compdt and (not lastcompdt or lastcompdt < compdt):
+                lastcompdt = compdt
+                lastcomp = comp
+
+        if not lastcomp:
+            # RFC says nothing about what to do when a given
+            # time is before the first onset date. We'll look for the
+            # first standard component, or the first component, if
+            # none is found.
+            for comp in self._comps:
+                if not comp.isdst:
+                    lastcomp = comp
+                    break
+            else:
+                lastcomp = comp[0]
+
+        self._cachedate.insert(0, (dt, self._fold(dt)))
+        self._cachecomp.insert(0, lastcomp)
+
+        if len(self._cachedate) > 10:
+            self._cachedate.pop()
+            self._cachecomp.pop()
+
+        return lastcomp
+
+    def _find_compdt(self, comp, dt):
+        if comp.tzoffsetdiff < ZERO and self._fold(dt):
+            dt -= comp.tzoffsetdiff
+
+        compdt = comp.rrule.before(dt, inc=True)
+
+        return compdt
+
+    def utcoffset(self, dt):
+        if dt is None:
+            return None
+
+        return self._find_comp(dt).tzoffsetto
+
+    def dst(self, dt):
+        comp = self._find_comp(dt)
+        if comp.isdst:
+            return comp.tzoffsetdiff
+        else:
+            return ZERO
+
+    @tzname_in_python2
+    def tzname(self, dt):
+        return self._find_comp(dt).tzname
+
+    def __repr__(self):
+        return "<tzicalvtz %s>" % repr(self._tzid)
+
+    __reduce__ = object.__reduce__
+
+
+class tzical(object):
+    """
+    This object is designed to parse an iCalendar-style ``VTIMEZONE`` structure
+    as set out in `RFC 2445`_ Section 4.6.5 into one or more `tzinfo` objects.
+
+    :param `fileobj`:
+        A file or stream in iCalendar format, which should be UTF-8 encoded
+        with CRLF endings.
+
+    .. _`RFC 2445`: https://www.ietf.org/rfc/rfc2445.txt
+    """
+    def __init__(self, fileobj):
+        global rrule
+        from dateutil import rrule
+
+        if isinstance(fileobj, string_types):
+            self._s = fileobj
+            # ical should be encoded in UTF-8 with CRLF
+            fileobj = open(fileobj, 'r')
+        else:
+            self._s = getattr(fileobj, 'name', repr(fileobj))
+            fileobj = _ContextWrapper(fileobj)
+
+        self._vtz = {}
+
+        with fileobj as fobj:
+            self._parse_rfc(fobj.read())
+
+    def keys(self):
+        """
+        Retrieves the available time zones as a list.
+        """
+        return list(self._vtz.keys())
+
+    def get(self, tzid=None):
+        """
+        Retrieve a :py:class:`datetime.tzinfo` object by its ``tzid``.
+
+        :param tzid:
+            If there is exactly one time zone available, omitting ``tzid``
+            or passing :py:const:`None` value returns it. Otherwise a valid
+            key (which can be retrieved from :func:`keys`) is required.
+
+        :raises ValueError:
+            Raised if ``tzid`` is not specified but there are either more
+            or fewer than 1 zone defined.
+
+        :returns:
+            Returns either a :py:class:`datetime.tzinfo` object representing
+            the relevant time zone or :py:const:`None` if the ``tzid`` was
+            not found.
+        """
+        if tzid is None:
+            if len(self._vtz) == 0:
+                raise ValueError("no timezones defined")
+            elif len(self._vtz) > 1:
+                raise ValueError("more than one timezone available")
+            tzid = next(iter(self._vtz))
+
+        return self._vtz.get(tzid)
+
+    def _parse_offset(self, s):
+        s = s.strip()
+        if not s:
+            raise ValueError("empty offset")
+        if s[0] in ('+', '-'):
+            signal = (-1, +1)[s[0] == '+']
+            s = s[1:]
+        else:
+            signal = +1
+        if len(s) == 4:
+            return (int(s[:2]) * 3600 + int(s[2:]) * 60) * signal
+        elif len(s) == 6:
+            return (int(s[:2]) * 3600 + int(s[2:4]) * 60 + int(s[4:])) * signal
+        else:
+            raise ValueError("invalid offset: " + s)
+
+    def _parse_rfc(self, s):
+        lines = s.splitlines()
+        if not lines:
+            raise ValueError("empty string")
+
+        # Unfold
+        i = 0
+        while i < len(lines):
+            line = lines[i].rstrip()
+            if not line:
+                del lines[i]
+            elif i > 0 and line[0] == " ":
+                lines[i-1] += line[1:]
+                del lines[i]
+            else:
+                i += 1
+
+        tzid = None
+        comps = []
+        invtz = False
+        comptype = None
+        for line in lines:
+            if not line:
+                continue
+            name, value = line.split(':', 1)
+            parms = name.split(';')
+            if not parms:
+                raise ValueError("empty property name")
+            name = parms[0].upper()
+            parms = parms[1:]
+            if invtz:
+                if name == "BEGIN":
+                    if value in ("STANDARD", "DAYLIGHT"):
+                        # Process component
+                        pass
+                    else:
+                        raise ValueError("unknown component: "+value)
+                    comptype = value
+                    founddtstart = False
+                    tzoffsetfrom = None
+                    tzoffsetto = None
+                    rrulelines = []
+                    tzname = None
+                elif name == "END":
+                    if value == "VTIMEZONE":
+                        if comptype:
+                            raise ValueError("component not closed: "+comptype)
+                        if not tzid:
+                            raise ValueError("mandatory TZID not found")
+                        if not comps:
+                            raise ValueError(
+                                "at least one component is needed")
+                        # Process vtimezone
+                        self._vtz[tzid] = _tzicalvtz(tzid, comps)
+                        invtz = False
+                    elif value == comptype:
+                        if not founddtstart:
+                            raise ValueError("mandatory DTSTART not found")
+                        if tzoffsetfrom is None:
+                            raise ValueError(
+                                "mandatory TZOFFSETFROM not found")
+                        if tzoffsetto is None:
+                            raise ValueError(
+                                "mandatory TZOFFSETFROM not found")
+                        # Process component
+                        rr = None
+                        if rrulelines:
+                            rr = rrule.rrulestr("\n".join(rrulelines),
+                                                compatible=True,
+                                                ignoretz=True,
+                                                cache=True)
+                        comp = _tzicalvtzcomp(tzoffsetfrom, tzoffsetto,
+                                              (comptype == "DAYLIGHT"),
+                                              tzname, rr)
+                        comps.append(comp)
+                        comptype = None
+                    else:
+                        raise ValueError("invalid component end: "+value)
+                elif comptype:
+                    if name == "DTSTART":
+                        rrulelines.append(line)
+                        founddtstart = True
+                    elif name in ("RRULE", "RDATE", "EXRULE", "EXDATE"):
+                        rrulelines.append(line)
+                    elif name == "TZOFFSETFROM":
+                        if parms:
+                            raise ValueError(
+                                "unsupported %s parm: %s " % (name, parms[0]))
+                        tzoffsetfrom = self._parse_offset(value)
+                    elif name == "TZOFFSETTO":
+                        if parms:
+                            raise ValueError(
+                                "unsupported TZOFFSETTO parm: "+parms[0])
+                        tzoffsetto = self._parse_offset(value)
+                    elif name == "TZNAME":
+                        if parms:
+                            raise ValueError(
+                                "unsupported TZNAME parm: "+parms[0])
+                        tzname = value
+                    elif name == "COMMENT":
+                        pass
+                    else:
+                        raise ValueError("unsupported property: "+name)
+                else:
+                    if name == "TZID":
+                        if parms:
+                            raise ValueError(
+                                "unsupported TZID parm: "+parms[0])
+                        tzid = value
+                    elif name in ("TZURL", "LAST-MODIFIED", "COMMENT"):
+                        pass
+                    else:
+                        raise ValueError("unsupported property: "+name)
+            elif name == "BEGIN" and value == "VTIMEZONE":
+                tzid = None
+                comps = []
+                invtz = True
+
+    def __repr__(self):
+        return "%s(%s)" % (self.__class__.__name__, repr(self._s))
+
+
+if sys.platform != "win32":
+    TZFILES = ["/etc/localtime", "localtime"]
+    TZPATHS = ["/usr/share/zoneinfo",
+               "/usr/lib/zoneinfo",
+               "/usr/share/lib/zoneinfo",
+               "/etc/zoneinfo"]
+else:
+    TZFILES = []
+    TZPATHS = []
+
+
+def gettz(name=None):
+    tz = None
+    if not name:
+        try:
+            name = os.environ["TZ"]
+        except KeyError:
+            pass
+    if name is None or name == ":":
+        for filepath in TZFILES:
+            if not os.path.isabs(filepath):
+                filename = filepath
+                for path in TZPATHS:
+                    filepath = os.path.join(path, filename)
+                    if os.path.isfile(filepath):
+                        break
+                else:
+                    continue
+            if os.path.isfile(filepath):
+                try:
+                    tz = tzfile(filepath)
+                    break
+                except (IOError, OSError, ValueError):
+                    pass
+        else:
+            tz = tzlocal()
+    else:
+        if name.startswith(":"):
+            name = name[:-1]
+        if os.path.isabs(name):
+            if os.path.isfile(name):
+                tz = tzfile(name)
+            else:
+                tz = None
+        else:
+            for path in TZPATHS:
+                filepath = os.path.join(path, name)
+                if not os.path.isfile(filepath):
+                    filepath = filepath.replace(' ', '_')
+                    if not os.path.isfile(filepath):
+                        continue
+                try:
+                    tz = tzfile(filepath)
+                    break
+                except (IOError, OSError, ValueError):
+                    pass
+            else:
+                tz = None
+                if tzwin is not None:
+                    try:
+                        tz = tzwin(name)
+                    except WindowsError:
+                        tz = None
+
+                if not tz:
+                    from dateutil.zoneinfo import get_zonefile_instance
+                    tz = get_zonefile_instance().get(name)
+
+                if not tz:
+                    for c in name:
+                        # name must have at least one offset to be a tzstr
+                        if c in "0123456789":
+                            try:
+                                tz = tzstr(name)
+                            except ValueError:
+                                pass
+                            break
+                    else:
+                        if name in ("GMT", "UTC"):
+                            tz = tzutc()
+                        elif name in time.tzname:
+                            tz = tzlocal()
+    return tz
+
+
+def datetime_exists(dt, tz=None):
+    """
+    Given a datetime and a time zone, determine whether or not a given datetime
+    would fall in a gap.
+
+    :param dt:
+        A :class:`datetime.datetime` (whose time zone will be ignored if ``tz``
+        is provided.)
+
+    :param tz:
+        A :class:`datetime.tzinfo` with support for the ``fold`` attribute. If
+        ``None`` or not provided, the datetime's own time zone will be used.
+
+    :return:
+        Returns a boolean value whether or not the "wall time" exists in ``tz``.
+    """
+    if tz is None:
+        if dt.tzinfo is None:
+            raise ValueError('Datetime is naive and no time zone provided.')
+        tz = dt.tzinfo
+
+    dt = dt.replace(tzinfo=None)
+
+    # This is essentially a test of whether or not the datetime can survive
+    # a round trip to UTC.
+    dt_rt = dt.replace(tzinfo=tz).astimezone(tzutc()).astimezone(tz)
+    dt_rt = dt_rt.replace(tzinfo=None)
+
+    return dt == dt_rt
+
+
+def datetime_ambiguous(dt, tz=None):
+    """
+    Given a datetime and a time zone, determine whether or not a given datetime
+    is ambiguous (i.e if there are two times differentiated only by their DST
+    status).
+
+    :param dt:
+        A :class:`datetime.datetime` (whose time zone will be ignored if ``tz``
+        is provided.)
+
+    :param tz:
+        A :class:`datetime.tzinfo` with support for the ``fold`` attribute. If
+        ``None`` or not provided, the datetime's own time zone will be used.
+
+    :return:
+        Returns a boolean value whether or not the "wall time" is ambiguous in
+        ``tz``.
+
+    .. versionadded:: 2.6.0
+    """
+    if tz is None:
+        if dt.tzinfo is None:
+            raise ValueError('Datetime is naive and no time zone provided.')
+
+        tz = dt.tzinfo
+
+    # If a time zone defines its own "is_ambiguous" function, we'll use that.
+    is_ambiguous_fn = getattr(tz, 'is_ambiguous', None)
+    if is_ambiguous_fn is not None:
+        try:
+            return tz.is_ambiguous(dt)
+        except:
+            pass
+
+    # If it doesn't come out and tell us it's ambiguous, we'll just check if
+    # the fold attribute has any effect on this particular date and time.
+    dt = dt.replace(tzinfo=tz)
+    wall_0 = enfold(dt, fold=0)
+    wall_1 = enfold(dt, fold=1)
+
+    same_offset = wall_0.utcoffset() == wall_1.utcoffset()
+    same_dst = wall_0.dst() == wall_1.dst()
+
+    return not (same_offset and same_dst)
+
+
+def _datetime_to_timestamp(dt):
+    """
+    Convert a :class:`datetime.datetime` object to an epoch timestamp in seconds
+    since January 1, 1970, ignoring the time zone.
+    """
+    return _total_seconds((dt.replace(tzinfo=None) - EPOCH))
+
+
+class _ContextWrapper(object):
+    """
+    Class for wrapping contexts so that they are passed through in a
+    with statement.
+    """
+    def __init__(self, context):
+        self.context = context
+
+    def __enter__(self):
+        return self.context
+
+    def __exit__(*args, **kwargs):
+        pass
+
+# vim:ts=4:sw=4:et
diff --git a/python/dateutil/tz/win.py b/python/dateutil/tz/win.py
new file mode 100644
index 0000000..36a1c26
--- /dev/null
+++ b/python/dateutil/tz/win.py
@@ -0,0 +1,332 @@
+# This code was originally contributed by Jeffrey Harris.
+import datetime
+import struct
+
+from six.moves import winreg
+from six import text_type
+
+try:
+    import ctypes
+    from ctypes import wintypes
+except ValueError:
+    # ValueError is raised on non-Windows systems for some horrible reason.
+    raise ImportError("Running tzwin on non-Windows system")
+
+from ._common import tzrangebase
+
+__all__ = ["tzwin", "tzwinlocal", "tzres"]
+
+ONEWEEK = datetime.timedelta(7)
+
+TZKEYNAMENT = r"SOFTWARE\Microsoft\Windows NT\CurrentVersion\Time Zones"
+TZKEYNAME9X = r"SOFTWARE\Microsoft\Windows\CurrentVersion\Time Zones"
+TZLOCALKEYNAME = r"SYSTEM\CurrentControlSet\Control\TimeZoneInformation"
+
+
+def _settzkeyname():
+    handle = winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE)
+    try:
+        winreg.OpenKey(handle, TZKEYNAMENT).Close()
+        TZKEYNAME = TZKEYNAMENT
+    except WindowsError:
+        TZKEYNAME = TZKEYNAME9X
+    handle.Close()
+    return TZKEYNAME
+
+
+TZKEYNAME = _settzkeyname()
+
+
+class tzres(object):
+    """
+    Class for accessing `tzres.dll`, which contains timezone name related
+    resources.
+
+    .. versionadded:: 2.5.0
+    """
+    p_wchar = ctypes.POINTER(wintypes.WCHAR)        # Pointer to a wide char
+
+    def __init__(self, tzres_loc='tzres.dll'):
+        # Load the user32 DLL so we can load strings from tzres
+        user32 = ctypes.WinDLL('user32')
+
+        # Specify the LoadStringW function
+        user32.LoadStringW.argtypes = (wintypes.HINSTANCE,
+                                       wintypes.UINT,
+                                       wintypes.LPWSTR,
+                                       ctypes.c_int)
+
+        self.LoadStringW = user32.LoadStringW
+        self._tzres = ctypes.WinDLL(tzres_loc)
+        self.tzres_loc = tzres_loc
+
+    def load_name(self, offset):
+        """
+        Load a timezone name from a DLL offset (integer).
+
+        >>> from dateutil.tzwin import tzres
+        >>> tzr = tzres()
+        >>> print(tzr.load_name(112))
+        'Eastern Standard Time'
+
+        :param offset:
+            A positive integer value referring to a string from the tzres dll.
+
+        ..note:
+            Offsets found in the registry are generally of the form
+            `@tzres.dll,-114`. The offset in this case if 114, not -114.
+
+        """
+        resource = self.p_wchar()
+        lpBuffer = ctypes.cast(ctypes.byref(resource), wintypes.LPWSTR)
+        nchar = self.LoadStringW(self._tzres._handle, offset, lpBuffer, 0)
+        return resource[:nchar]
+
+    def name_from_string(self, tzname_str):
+        """
+        Parse strings as returned from the Windows registry into the time zone
+        name as defined in the registry.
+
+        >>> from dateutil.tzwin import tzres
+        >>> tzr = tzres()
+        >>> print(tzr.name_from_string('@tzres.dll,-251'))
+        'Dateline Daylight Time'
+        >>> print(tzr.name_from_string('Eastern Standard Time'))
+        'Eastern Standard Time'
+
+        :param tzname_str:
+            A timezone name string as returned from a Windows registry key.
+
+        :return:
+            Returns the localized timezone string from tzres.dll if the string
+            is of the form `@tzres.dll,-offset`, else returns the input string.
+        """
+        if not tzname_str.startswith('@'):
+            return tzname_str
+
+        name_splt = tzname_str.split(',-')
+        try:
+            offset = int(name_splt[1])
+        except:
+            raise ValueError("Malformed timezone string.")
+
+        return self.load_name(offset)
+
+
+class tzwinbase(tzrangebase):
+    """tzinfo class based on win32's timezones available in the registry."""
+    def __init__(self):
+        raise NotImplementedError('tzwinbase is an abstract base class')
+
+    def __eq__(self, other):
+        # Compare on all relevant dimensions, including name.
+        if not isinstance(other, tzwinbase):
+            return NotImplemented
+
+        return  (self._std_offset == other._std_offset and
+                 self._dst_offset == other._dst_offset and
+                 self._stddayofweek == other._stddayofweek and
+                 self._dstdayofweek == other._dstdayofweek and
+                 self._stdweeknumber == other._stdweeknumber and
+                 self._dstweeknumber == other._dstweeknumber and
+                 self._stdhour == other._stdhour and
+                 self._dsthour == other._dsthour and
+                 self._stdminute == other._stdminute and
+                 self._dstminute == other._dstminute and
+                 self._std_abbr == other._std_abbr and
+                 self._dst_abbr == other._dst_abbr)
+
+    @staticmethod
+    def list():
+        """Return a list of all time zones known to the system."""
+        with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
+            with winreg.OpenKey(handle, TZKEYNAME) as tzkey:
+                result = [winreg.EnumKey(tzkey, i)
+                          for i in range(winreg.QueryInfoKey(tzkey)[0])]
+        return result
+
+    def display(self):
+        return self._display
+
+    def transitions(self, year):
+        """
+        For a given year, get the DST on and off transition times, expressed
+        always on the standard time side. For zones with no transitions, this
+        function returns ``None``.
+
+        :param year:
+            The year whose transitions you would like to query.
+
+        :return:
+            Returns a :class:`tuple` of :class:`datetime.datetime` objects,
+            ``(dston, dstoff)`` for zones with an annual DST transition, or
+            ``None`` for fixed offset zones.
+        """
+
+        if not self.hasdst:
+            return None
+
+        dston = picknthweekday(year, self._dstmonth, self._dstdayofweek,
+                               self._dsthour, self._dstminute,
+                               self._dstweeknumber)
+
+        dstoff = picknthweekday(year, self._stdmonth, self._stddayofweek,
+                                self._stdhour, self._stdminute,
+                                self._stdweeknumber)
+
+        # Ambiguous dates default to the STD side
+        dstoff -= self._dst_base_offset
+
+        return dston, dstoff
+
+    def _get_hasdst(self):
+        return self._dstmonth != 0
+
+    @property
+    def _dst_base_offset(self):
+        return self._dst_base_offset_
+
+
+class tzwin(tzwinbase):
+
+    def __init__(self, name):
+        self._name = name
+
+        # multiple contexts only possible in 2.7 and 3.1, we still support 2.6
+        with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
+            tzkeyname = text_type("{kn}\\{name}").format(kn=TZKEYNAME, name=name)
+            with winreg.OpenKey(handle, tzkeyname) as tzkey:
+                keydict = valuestodict(tzkey)
+
+        self._std_abbr = keydict["Std"]
+        self._dst_abbr = keydict["Dlt"]
+
+        self._display = keydict["Display"]
+
+        # See http://ww_winreg.jsiinc.com/SUBA/tip0300/rh0398.htm
+        tup = struct.unpack("=3l16h", keydict["TZI"])
+        stdoffset = -tup[0]-tup[1]          # Bias + StandardBias * -1
+        dstoffset = stdoffset-tup[2]        # + DaylightBias * -1
+        self._std_offset = datetime.timedelta(minutes=stdoffset)
+        self._dst_offset = datetime.timedelta(minutes=dstoffset)
+
+        # for the meaning see the win32 TIME_ZONE_INFORMATION structure docs
+        # http://msdn.microsoft.com/en-us/library/windows/desktop/ms725481(v=vs.85).aspx
+        (self._stdmonth,
+         self._stddayofweek,   # Sunday = 0
+         self._stdweeknumber,  # Last = 5
+         self._stdhour,
+         self._stdminute) = tup[4:9]
+
+        (self._dstmonth,
+         self._dstdayofweek,   # Sunday = 0
+         self._dstweeknumber,  # Last = 5
+         self._dsthour,
+         self._dstminute) = tup[12:17]
+
+        self._dst_base_offset_ = self._dst_offset - self._std_offset
+        self.hasdst = self._get_hasdst()
+
+    def __repr__(self):
+        return "tzwin(%s)" % repr(self._name)
+
+    def __reduce__(self):
+        return (self.__class__, (self._name,))
+
+
+class tzwinlocal(tzwinbase):
+    def __init__(self):
+        with winreg.ConnectRegistry(None, winreg.HKEY_LOCAL_MACHINE) as handle:
+            with winreg.OpenKey(handle, TZLOCALKEYNAME) as tzlocalkey:
+                keydict = valuestodict(tzlocalkey)
+
+            self._std_abbr = keydict["StandardName"]
+            self._dst_abbr = keydict["DaylightName"]
+
+            try:
+                tzkeyname = text_type('{kn}\\{sn}').format(kn=TZKEYNAME,
+                                                          sn=self._std_abbr)
+                with winreg.OpenKey(handle, tzkeyname) as tzkey:
+                    _keydict = valuestodict(tzkey)
+                    self._display = _keydict["Display"]
+            except OSError:
+                self._display = None
+
+        stdoffset = -keydict["Bias"]-keydict["StandardBias"]
+        dstoffset = stdoffset-keydict["DaylightBias"]
+
+        self._std_offset = datetime.timedelta(minutes=stdoffset)
+        self._dst_offset = datetime.timedelta(minutes=dstoffset)
+
+        # For reasons unclear, in this particular key, the day of week has been
+        # moved to the END of the SYSTEMTIME structure.
+        tup = struct.unpack("=8h", keydict["StandardStart"])
+
+        (self._stdmonth,
+         self._stdweeknumber,  # Last = 5
+         self._stdhour,
+         self._stdminute) = tup[1:5]
+
+        self._stddayofweek = tup[7]
+
+        tup = struct.unpack("=8h", keydict["DaylightStart"])
+
+        (self._dstmonth,
+         self._dstweeknumber,  # Last = 5
+         self._dsthour,
+         self._dstminute) = tup[1:5]
+
+        self._dstdayofweek = tup[7]
+
+        self._dst_base_offset_ = self._dst_offset - self._std_offset
+        self.hasdst = self._get_hasdst()
+
+    def __repr__(self):
+        return "tzwinlocal()"
+
+    def __str__(self):
+        # str will return the standard name, not the daylight name.
+        return "tzwinlocal(%s)" % repr(self._std_abbr)
+
+    def __reduce__(self):
+        return (self.__class__, ())
+
+
+def picknthweekday(year, month, dayofweek, hour, minute, whichweek):
+    """ dayofweek == 0 means Sunday, whichweek 5 means last instance """
+    first = datetime.datetime(year, month, 1, hour, minute)
+
+    # This will work if dayofweek is ISO weekday (1-7) or Microsoft-style (0-6),
+    # Because 7 % 7 = 0
+    weekdayone = first.replace(day=((dayofweek - first.isoweekday()) % 7) + 1)
+    wd = weekdayone + ((whichweek - 1) * ONEWEEK)
+    if (wd.month != month):
+        wd -= ONEWEEK
+
+    return wd
+
+
+def valuestodict(key):
+    """Convert a registry key's values to a dictionary."""
+    dout = {}
+    size = winreg.QueryInfoKey(key)[1]
+    tz_res = None
+
+    for i in range(size):
+        key_name, value, dtype = winreg.EnumValue(key, i)
+        if dtype == winreg.REG_DWORD or dtype == winreg.REG_DWORD_LITTLE_ENDIAN:
+            # If it's a DWORD (32-bit integer), it's stored as unsigned - convert
+            # that to a proper signed integer
+            if value & (1 << 31):
+                value = value - (1 << 32)
+        elif dtype == winreg.REG_SZ:
+            # If it's a reference to the tzres DLL, load the actual string
+            if value.startswith('@tzres'):
+                tz_res = tz_res or tzres()
+                value = tz_res.name_from_string(value)
+
+            value = value.rstrip('\x00')    # Remove trailing nulls
+
+        dout[key_name] = value
+
+    return dout
diff --git a/python/dateutil/tzwin.py b/python/dateutil/tzwin.py
new file mode 100644
index 0000000..cebc673
--- /dev/null
+++ b/python/dateutil/tzwin.py
@@ -0,0 +1,2 @@
+# tzwin has moved to dateutil.tz.win
+from .tz.win import *
diff --git a/python/dateutil/zoneinfo/__init__.py b/python/dateutil/zoneinfo/__init__.py
new file mode 100644
index 0000000..a2ed4f9
--- /dev/null
+++ b/python/dateutil/zoneinfo/__init__.py
@@ -0,0 +1,183 @@
+# -*- coding: utf-8 -*-
+import warnings
+import json
+
+from tarfile import TarFile
+from pkgutil import get_data
+from io import BytesIO
+from contextlib import closing
+
+from dateutil.tz import tzfile
+
+__all__ = ["get_zonefile_instance", "gettz", "gettz_db_metadata", "rebuild"]
+
+ZONEFILENAME = "dateutil-zoneinfo.tar.gz"
+METADATA_FN = 'METADATA'
+
+# python2.6 compatability. Note that TarFile.__exit__ != TarFile.close, but
+# it's close enough for python2.6
+tar_open = TarFile.open
+if not hasattr(TarFile, '__exit__'):
+    def tar_open(*args, **kwargs):
+        return closing(TarFile.open(*args, **kwargs))
+
+
+class tzfile(tzfile):
+    def __reduce__(self):
+        return (gettz, (self._filename,))
+
+
+def getzoneinfofile_stream():
+    try:
+        return BytesIO(get_data(__name__, ZONEFILENAME))
+    except IOError as e:  # TODO  switch to FileNotFoundError?
+        warnings.warn("I/O error({0}): {1}".format(e.errno, e.strerror))
+        return None
+
+
+class ZoneInfoFile(object):
+    def __init__(self, zonefile_stream=None):
+        if zonefile_stream is not None:
+            with tar_open(fileobj=zonefile_stream, mode='r') as tf:
+                # dict comprehension does not work on python2.6
+                # TODO: get back to the nicer syntax when we ditch python2.6
+                # self.zones = {zf.name: tzfile(tf.extractfile(zf),
+                #               filename = zf.name)
+                #              for zf in tf.getmembers() if zf.isfile()}
+                self.zones = dict((zf.name, tzfile(tf.extractfile(zf),
+                                                   filename=zf.name))
+                                  for zf in tf.getmembers()
+                                  if zf.isfile() and zf.name != METADATA_FN)
+                # deal with links: They'll point to their parent object. Less
+                # waste of memory
+                # links = {zl.name: self.zones[zl.linkname]
+                #        for zl in tf.getmembers() if zl.islnk() or zl.issym()}
+                links = dict((zl.name, self.zones[zl.linkname])
+                             for zl in tf.getmembers() if
+                             zl.islnk() or zl.issym())
+                self.zones.update(links)
+                try:
+                    metadata_json = tf.extractfile(tf.getmember(METADATA_FN))
+                    metadata_str = metadata_json.read().decode('UTF-8')
+                    self.metadata = json.loads(metadata_str)
+                except KeyError:
+                    # no metadata in tar file
+                    self.metadata = None
+        else:
+            self.zones = dict()
+            self.metadata = None
+
+    def get(self, name, default=None):
+        """
+        Wrapper for :func:`ZoneInfoFile.zones.get`. This is a convenience method
+        for retrieving zones from the zone dictionary.
+
+        :param name:
+            The name of the zone to retrieve. (Generally IANA zone names)
+
+        :param default:
+            The value to return in the event of a missing key.
+
+        .. versionadded:: 2.6.0
+
+        """
+        return self.zones.get(name, default)
+
+
+# The current API has gettz as a module function, although in fact it taps into
+# a stateful class. So as a workaround for now, without changing the API, we
+# will create a new "global" class instance the first time a user requests a
+# timezone. Ugly, but adheres to the api.
+#
+# TODO: Remove after deprecation period.
+_CLASS_ZONE_INSTANCE = list()
+
+
+def get_zonefile_instance(new_instance=False):
+    """
+    This is a convenience function which provides a :class:`ZoneInfoFile`
+    instance using the data provided by the ``dateutil`` package. By default, it
+    caches a single instance of the ZoneInfoFile object and returns that.
+
+    :param new_instance:
+        If ``True``, a new instance of :class:`ZoneInfoFile` is instantiated and
+        used as the cached instance for the next call. Otherwise, new instances
+        are created only as necessary.
+
+    :return:
+        Returns a :class:`ZoneInfoFile` object.
+
+    .. versionadded:: 2.6
+    """
+    if new_instance:
+        zif = None
+    else:
+        zif = getattr(get_zonefile_instance, '_cached_instance', None)
+
+    if zif is None:
+        zif = ZoneInfoFile(getzoneinfofile_stream())
+
+        get_zonefile_instance._cached_instance = zif
+
+    return zif
+
+
+def gettz(name):
+    """
+    This retrieves a time zone from the local zoneinfo tarball that is packaged
+    with dateutil.
+
+    :param name:
+        An IANA-style time zone name, as found in the zoneinfo file.
+
+    :return:
+        Returns a :class:`dateutil.tz.tzfile` time zone object.
+
+    .. warning::
+        It is generally inadvisable to use this function, and it is only
+        provided for API compatibility with earlier versions. This is *not*
+        equivalent to ``dateutil.tz.gettz()``, which selects an appropriate
+        time zone based on the inputs, favoring system zoneinfo. This is ONLY
+        for accessing the dateutil-specific zoneinfo (which may be out of
+        date compared to the system zoneinfo).
+
+    .. deprecated:: 2.6
+        If you need to use a specific zoneinfofile over the system zoneinfo,
+        instantiate a :class:`dateutil.zoneinfo.ZoneInfoFile` object and call
+        :func:`dateutil.zoneinfo.ZoneInfoFile.get(name)` instead.
+
+        Use :func:`get_zonefile_instance` to retrieve an instance of the
+        dateutil-provided zoneinfo.
+    """
+    warnings.warn("zoneinfo.gettz() will be removed in future versions, "
+                  "to use the dateutil-provided zoneinfo files, instantiate a "
+                  "ZoneInfoFile object and use ZoneInfoFile.zones.get() "
+                  "instead. See the documentation for details.",
+                  DeprecationWarning)
+
+    if len(_CLASS_ZONE_INSTANCE) == 0:
+        _CLASS_ZONE_INSTANCE.append(ZoneInfoFile(getzoneinfofile_stream()))
+    return _CLASS_ZONE_INSTANCE[0].zones.get(name)
+
+
+def gettz_db_metadata():
+    """ Get the zonefile metadata
+
+    See `zonefile_metadata`_
+
+    :returns:
+        A dictionary with the database metadata
+
+    .. deprecated:: 2.6
+        See deprecation warning in :func:`zoneinfo.gettz`. To get metadata,
+        query the attribute ``zoneinfo.ZoneInfoFile.metadata``.
+    """
+    warnings.warn("zoneinfo.gettz_db_metadata() will be removed in future "
+                  "versions, to use the dateutil-provided zoneinfo files, "
+                  "ZoneInfoFile object and query the 'metadata' attribute "
+                  "instead. See the documentation for details.",
+                  DeprecationWarning)
+
+    if len(_CLASS_ZONE_INSTANCE) == 0:
+        _CLASS_ZONE_INSTANCE.append(ZoneInfoFile(getzoneinfofile_stream()))
+    return _CLASS_ZONE_INSTANCE[0].metadata
diff --git a/python/dateutil/zoneinfo/dateutil-zoneinfo.tar.gz b/python/dateutil/zoneinfo/dateutil-zoneinfo.tar.gz
new file mode 100644
index 0000000..613c0ff
--- /dev/null
+++ b/python/dateutil/zoneinfo/dateutil-zoneinfo.tar.gz
diff --git a/python/dateutil/zoneinfo/rebuild.py b/python/dateutil/zoneinfo/rebuild.py
new file mode 100644
index 0000000..9d53bb8
--- /dev/null
+++ b/python/dateutil/zoneinfo/rebuild.py
@@ -0,0 +1,52 @@
+import logging
+import os
+import tempfile
+import shutil
+import json
+from subprocess import check_call
+
+from dateutil.zoneinfo import tar_open, METADATA_FN, ZONEFILENAME
+
+
+def rebuild(filename, tag=None, format="gz", zonegroups=[], metadata=None):
+    """Rebuild the internal timezone info in dateutil/zoneinfo/zoneinfo*tar*
+
+    filename is the timezone tarball from ftp.iana.org/tz.
+
+    """
+    tmpdir = tempfile.mkdtemp()
+    zonedir = os.path.join(tmpdir, "zoneinfo")
+    moduledir = os.path.dirname(__file__)
+    try:
+        with tar_open(filename) as tf:
+            for name in zonegroups:
+                tf.extract(name, tmpdir)
+            filepaths = [os.path.join(tmpdir, n) for n in zonegroups]
+            try:
+                check_call(["zic", "-d", zonedir] + filepaths)
+            except OSError as e:
+                _print_on_nosuchfile(e)
+                raise
+        # write metadata file
+        with open(os.path.join(zonedir, METADATA_FN), 'w') as f:
+            json.dump(metadata, f, indent=4, sort_keys=True)
+        target = os.path.join(moduledir, ZONEFILENAME)
+        with tar_open(target, "w:%s" % format) as tf:
+            for entry in os.listdir(zonedir):
+                entrypath = os.path.join(zonedir, entry)
+                tf.add(entrypath, entry)
+    finally:
+        shutil.rmtree(tmpdir)
+
+
+def _print_on_nosuchfile(e):
+    """Print helpful troubleshooting message
+
+    e is an exception raised by subprocess.check_call()
+
+    """
+    if e.errno == 2:
+        logging.error(
+            "Could not find zic. Perhaps you need to install "
+            "libc-bin or some other package that provides it, "
+            "or it's not in your PATH?")
diff --git a/python/defusedxml/ElementTree.py b/python/defusedxml/ElementTree.py
new file mode 100644
index 0000000..41b2ea8
--- /dev/null
+++ b/python/defusedxml/ElementTree.py
@@ -0,0 +1,112 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.etree.ElementTree facade
+"""
+from __future__ import print_function, absolute_import
+
+import sys
+from xml.etree.ElementTree import TreeBuilder as _TreeBuilder
+from xml.etree.ElementTree import parse as _parse
+from xml.etree.ElementTree import tostring
+
+from .common import PY3
+
+
+if PY3:
+    import importlib
+else:
+    from xml.etree.ElementTree import XMLParser as _XMLParser
+    from xml.etree.ElementTree import iterparse as _iterparse
+    from xml.etree.ElementTree import ParseError
+
+
+from .common import (DTDForbidden, EntitiesForbidden,
+                     ExternalReferenceForbidden, _generate_etree_functions)
+
+__origin__ = "xml.etree.ElementTree"
+
+
+def _get_py3_cls():
+    """Python 3.3 hides the pure Python code but defusedxml requires it.
+
+    The code is based on test.support.import_fresh_module().
+    """
+    pymodname = "xml.etree.ElementTree"
+    cmodname = "_elementtree"
+
+    pymod = sys.modules.pop(pymodname, None)
+    cmod = sys.modules.pop(cmodname, None)
+
+    sys.modules[cmodname] = None
+    pure_pymod = importlib.import_module(pymodname)
+    if cmod is not None:
+        sys.modules[cmodname] = cmod
+    else:
+        sys.modules.pop(cmodname)
+    sys.modules[pymodname] = pymod
+
+    _XMLParser = pure_pymod.XMLParser
+    _iterparse = pure_pymod.iterparse
+    ParseError = pure_pymod.ParseError
+
+    return _XMLParser, _iterparse, ParseError
+
+
+if PY3:
+    _XMLParser, _iterparse, ParseError = _get_py3_cls()
+
+
+class DefusedXMLParser(_XMLParser):
+
+    def __init__(self, html=0, target=None, encoding=None,
+                 forbid_dtd=False, forbid_entities=True,
+                 forbid_external=True):
+        # Python 2.x old style class
+        _XMLParser.__init__(self, html, target, encoding)
+        self.forbid_dtd = forbid_dtd
+        self.forbid_entities = forbid_entities
+        self.forbid_external = forbid_external
+        if PY3:
+            parser = self.parser
+        else:
+            parser = self._parser
+        if self.forbid_dtd:
+            parser.StartDoctypeDeclHandler = self.defused_start_doctype_decl
+        if self.forbid_entities:
+            parser.EntityDeclHandler = self.defused_entity_decl
+            parser.UnparsedEntityDeclHandler = self.defused_unparsed_entity_decl
+        if self.forbid_external:
+            parser.ExternalEntityRefHandler = self.defused_external_entity_ref_handler
+
+    def defused_start_doctype_decl(self, name, sysid, pubid,
+                                   has_internal_subset):
+        raise DTDForbidden(name, sysid, pubid)
+
+    def defused_entity_decl(self, name, is_parameter_entity, value, base,
+                            sysid, pubid, notation_name):
+        raise EntitiesForbidden(name, value, base, sysid, pubid, notation_name)
+
+    def defused_unparsed_entity_decl(self, name, base, sysid, pubid,
+                                     notation_name):
+        # expat 1.2
+        raise EntitiesForbidden(name, None, base, sysid, pubid, notation_name)
+
+    def defused_external_entity_ref_handler(self, context, base, sysid,
+                                            pubid):
+        raise ExternalReferenceForbidden(context, base, sysid, pubid)
+
+
+# aliases
+XMLTreeBuilder = XMLParse = DefusedXMLParser
+
+parse, iterparse, fromstring = _generate_etree_functions(DefusedXMLParser,
+                                                         _TreeBuilder, _parse,
+                                                         _iterparse)
+XML = fromstring
+
+
+__all__ = ['XML', 'XMLParse', 'XMLTreeBuilder', 'fromstring', 'iterparse',
+           'parse', 'tostring']
diff --git a/python/defusedxml/__init__.py b/python/defusedxml/__init__.py
new file mode 100644
index 0000000..590a5a9
--- /dev/null
+++ b/python/defusedxml/__init__.py
@@ -0,0 +1,45 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defuse XML bomb denial of service vulnerabilities
+"""
+from __future__ import print_function, absolute_import
+
+from .common import (DefusedXmlException, DTDForbidden, EntitiesForbidden,
+                     ExternalReferenceForbidden, NotSupportedError,
+                     _apply_defusing)
+
+
+def defuse_stdlib():
+    """Monkey patch and defuse all stdlib packages
+
+    :warning: The monkey patch is an EXPERIMETNAL feature.
+    """
+    defused = {}
+
+    from . import cElementTree
+    from . import ElementTree
+    from . import minidom
+    from . import pulldom
+    from . import sax
+    from . import expatbuilder
+    from . import expatreader
+    from . import xmlrpc
+
+    xmlrpc.monkey_patch()
+    defused[xmlrpc] = None
+
+    for defused_mod in [cElementTree, ElementTree, minidom, pulldom, sax,
+                        expatbuilder, expatreader]:
+        stdlib_mod = _apply_defusing(defused_mod)
+        defused[defused_mod] = stdlib_mod
+
+    return defused
+
+
+__version__ = "0.5.0"
+
+__all__ = ['DefusedXmlException', 'DTDForbidden', 'EntitiesForbidden',
+           'ExternalReferenceForbidden', 'NotSupportedError']
diff --git a/python/defusedxml/cElementTree.py b/python/defusedxml/cElementTree.py
new file mode 100644
index 0000000..cc13689
--- /dev/null
+++ b/python/defusedxml/cElementTree.py
@@ -0,0 +1,30 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.etree.cElementTree
+"""
+from __future__ import absolute_import
+
+from xml.etree.cElementTree import TreeBuilder as _TreeBuilder
+from xml.etree.cElementTree import parse as _parse
+from xml.etree.cElementTree import tostring
+# iterparse from ElementTree!
+from xml.etree.ElementTree import iterparse as _iterparse
+
+from .ElementTree import DefusedXMLParser
+from .common import _generate_etree_functions
+
+__origin__ = "xml.etree.cElementTree"
+
+
+XMLTreeBuilder = XMLParse = DefusedXMLParser
+
+parse, iterparse, fromstring = _generate_etree_functions(DefusedXMLParser,
+                                                         _TreeBuilder, _parse,
+                                                         _iterparse)
+XML = fromstring
+
+__all__ = ['XML', 'XMLParse', 'XMLTreeBuilder', 'fromstring', 'iterparse',
+           'parse', 'tostring']
diff --git a/python/defusedxml/common.py b/python/defusedxml/common.py
new file mode 100644
index 0000000..668b609
--- /dev/null
+++ b/python/defusedxml/common.py
@@ -0,0 +1,120 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Common constants, exceptions and helpe functions
+"""
+import sys
+
+PY3 = sys.version_info[0] == 3
+
+
+class DefusedXmlException(ValueError):
+    """Base exception
+    """
+
+    def __repr__(self):
+        return str(self)
+
+
+class DTDForbidden(DefusedXmlException):
+    """Document type definition is forbidden
+    """
+
+    def __init__(self, name, sysid, pubid):
+        super(DTDForbidden, self).__init__()
+        self.name = name
+        self.sysid = sysid
+        self.pubid = pubid
+
+    def __str__(self):
+        tpl = "DTDForbidden(name='{}', system_id={!r}, public_id={!r})"
+        return tpl.format(self.name, self.sysid, self.pubid)
+
+
+class EntitiesForbidden(DefusedXmlException):
+    """Entity definition is forbidden
+    """
+
+    def __init__(self, name, value, base, sysid, pubid, notation_name):
+        super(EntitiesForbidden, self).__init__()
+        self.name = name
+        self.value = value
+        self.base = base
+        self.sysid = sysid
+        self.pubid = pubid
+        self.notation_name = notation_name
+
+    def __str__(self):
+        tpl = "EntitiesForbidden(name='{}', system_id={!r}, public_id={!r})"
+        return tpl.format(self.name, self.sysid, self.pubid)
+
+
+class ExternalReferenceForbidden(DefusedXmlException):
+    """Resolving an external reference is forbidden
+    """
+
+    def __init__(self, context, base, sysid, pubid):
+        super(ExternalReferenceForbidden, self).__init__()
+        self.context = context
+        self.base = base
+        self.sysid = sysid
+        self.pubid = pubid
+
+    def __str__(self):
+        tpl = "ExternalReferenceForbidden(system_id='{}', public_id={})"
+        return tpl.format(self.sysid, self.pubid)
+
+
+class NotSupportedError(DefusedXmlException):
+    """The operation is not supported
+    """
+
+
+def _apply_defusing(defused_mod):
+    assert defused_mod is sys.modules[defused_mod.__name__]
+    stdlib_name = defused_mod.__origin__
+    __import__(stdlib_name, {}, {}, ["*"])
+    stdlib_mod = sys.modules[stdlib_name]
+    stdlib_names = set(dir(stdlib_mod))
+    for name, obj in vars(defused_mod).items():
+        if name.startswith("_") or name not in stdlib_names:
+            continue
+        setattr(stdlib_mod, name, obj)
+    return stdlib_mod
+
+
+def _generate_etree_functions(DefusedXMLParser, _TreeBuilder,
+                              _parse, _iterparse):
+    """Factory for functions needed by etree, dependent on whether
+    cElementTree or ElementTree is used."""
+
+    def parse(source, parser=None, forbid_dtd=False, forbid_entities=True,
+              forbid_external=True):
+        if parser is None:
+            parser = DefusedXMLParser(target=_TreeBuilder(),
+                                      forbid_dtd=forbid_dtd,
+                                      forbid_entities=forbid_entities,
+                                      forbid_external=forbid_external)
+        return _parse(source, parser)
+
+    def iterparse(source, events=None, parser=None, forbid_dtd=False,
+                  forbid_entities=True, forbid_external=True):
+        if parser is None:
+            parser = DefusedXMLParser(target=_TreeBuilder(),
+                                      forbid_dtd=forbid_dtd,
+                                      forbid_entities=forbid_entities,
+                                      forbid_external=forbid_external)
+        return _iterparse(source, events, parser)
+
+    def fromstring(text, forbid_dtd=False, forbid_entities=True,
+                   forbid_external=True):
+        parser = DefusedXMLParser(target=_TreeBuilder(),
+                                  forbid_dtd=forbid_dtd,
+                                  forbid_entities=forbid_entities,
+                                  forbid_external=forbid_external)
+        parser.feed(text)
+        return parser.close()
+
+    return parse, iterparse, fromstring
diff --git a/python/defusedxml/expatbuilder.py b/python/defusedxml/expatbuilder.py
new file mode 100644
index 0000000..0eb6b91
--- /dev/null
+++ b/python/defusedxml/expatbuilder.py
@@ -0,0 +1,110 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.dom.expatbuilder
+"""
+from __future__ import print_function, absolute_import
+
+from xml.dom.expatbuilder import ExpatBuilder as _ExpatBuilder
+from xml.dom.expatbuilder import Namespaces as _Namespaces
+
+from .common import (DTDForbidden, EntitiesForbidden,
+                     ExternalReferenceForbidden)
+
+__origin__ = "xml.dom.expatbuilder"
+
+
+class DefusedExpatBuilder(_ExpatBuilder):
+    """Defused document builder"""
+
+    def __init__(self, options=None, forbid_dtd=False, forbid_entities=True,
+                 forbid_external=True):
+        _ExpatBuilder.__init__(self, options)
+        self.forbid_dtd = forbid_dtd
+        self.forbid_entities = forbid_entities
+        self.forbid_external = forbid_external
+
+    def defused_start_doctype_decl(self, name, sysid, pubid,
+                                   has_internal_subset):
+        raise DTDForbidden(name, sysid, pubid)
+
+    def defused_entity_decl(self, name, is_parameter_entity, value, base,
+                            sysid, pubid, notation_name):
+        raise EntitiesForbidden(name, value, base, sysid, pubid, notation_name)
+
+    def defused_unparsed_entity_decl(self, name, base, sysid, pubid,
+                                     notation_name):
+        # expat 1.2
+        raise EntitiesForbidden(name, None, base, sysid, pubid, notation_name)
+
+    def defused_external_entity_ref_handler(self, context, base, sysid,
+                                            pubid):
+        raise ExternalReferenceForbidden(context, base, sysid, pubid)
+
+    def install(self, parser):
+        _ExpatBuilder.install(self, parser)
+
+        if self.forbid_dtd:
+            parser.StartDoctypeDeclHandler = self.defused_start_doctype_decl
+        if self.forbid_entities:
+            # if self._options.entities:
+            parser.EntityDeclHandler = self.defused_entity_decl
+            parser.UnparsedEntityDeclHandler = self.defused_unparsed_entity_decl
+        if self.forbid_external:
+            parser.ExternalEntityRefHandler = self.defused_external_entity_ref_handler
+
+
+class DefusedExpatBuilderNS(_Namespaces, DefusedExpatBuilder):
+    """Defused document builder that supports namespaces."""
+
+    def install(self, parser):
+        DefusedExpatBuilder.install(self, parser)
+        if self._options.namespace_declarations:
+            parser.StartNamespaceDeclHandler = (
+                self.start_namespace_decl_handler)
+
+    def reset(self):
+        DefusedExpatBuilder.reset(self)
+        self._initNamespaces()
+
+
+def parse(file, namespaces=True, forbid_dtd=False, forbid_entities=True,
+          forbid_external=True):
+    """Parse a document, returning the resulting Document node.
+
+    'file' may be either a file name or an open file object.
+    """
+    if namespaces:
+        build_builder = DefusedExpatBuilderNS
+    else:
+        build_builder = DefusedExpatBuilder
+    builder = build_builder(forbid_dtd=forbid_dtd,
+                            forbid_entities=forbid_entities,
+                            forbid_external=forbid_external)
+
+    if isinstance(file, str):
+        fp = open(file, 'rb')
+        try:
+            result = builder.parseFile(fp)
+        finally:
+            fp.close()
+    else:
+        result = builder.parseFile(file)
+    return result
+
+
+def parseString(string, namespaces=True, forbid_dtd=False,
+                forbid_entities=True, forbid_external=True):
+    """Parse a document from a string, returning the resulting
+    Document node.
+    """
+    if namespaces:
+        build_builder = DefusedExpatBuilderNS
+    else:
+        build_builder = DefusedExpatBuilder
+    builder = build_builder(forbid_dtd=forbid_dtd,
+                            forbid_entities=forbid_entities,
+                            forbid_external=forbid_external)
+    return builder.parseString(string)
diff --git a/python/defusedxml/expatreader.py b/python/defusedxml/expatreader.py
new file mode 100644
index 0000000..ef6bc39
--- /dev/null
+++ b/python/defusedxml/expatreader.py
@@ -0,0 +1,59 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.sax.expatreader
+"""
+from __future__ import print_function, absolute_import
+
+from xml.sax.expatreader import ExpatParser as _ExpatParser
+
+from .common import (DTDForbidden, EntitiesForbidden,
+                     ExternalReferenceForbidden)
+
+__origin__ = "xml.sax.expatreader"
+
+
+class DefusedExpatParser(_ExpatParser):
+    """Defused SAX driver for the pyexpat C module."""
+
+    def __init__(self, namespaceHandling=0, bufsize=2 ** 16 - 20,
+                 forbid_dtd=False, forbid_entities=True,
+                 forbid_external=True):
+        _ExpatParser.__init__(self, namespaceHandling, bufsize)
+        self.forbid_dtd = forbid_dtd
+        self.forbid_entities = forbid_entities
+        self.forbid_external = forbid_external
+
+    def defused_start_doctype_decl(self, name, sysid, pubid,
+                                   has_internal_subset):
+        raise DTDForbidden(name, sysid, pubid)
+
+    def defused_entity_decl(self, name, is_parameter_entity, value, base,
+                            sysid, pubid, notation_name):
+        raise EntitiesForbidden(name, value, base, sysid, pubid, notation_name)
+
+    def defused_unparsed_entity_decl(self, name, base, sysid, pubid,
+                                     notation_name):
+        # expat 1.2
+        raise EntitiesForbidden(name, None, base, sysid, pubid, notation_name)
+
+    def defused_external_entity_ref_handler(self, context, base, sysid,
+                                            pubid):
+        raise ExternalReferenceForbidden(context, base, sysid, pubid)
+
+    def reset(self):
+        _ExpatParser.reset(self)
+        parser = self._parser
+        if self.forbid_dtd:
+            parser.StartDoctypeDeclHandler = self.defused_start_doctype_decl
+        if self.forbid_entities:
+            parser.EntityDeclHandler = self.defused_entity_decl
+            parser.UnparsedEntityDeclHandler = self.defused_unparsed_entity_decl
+        if self.forbid_external:
+            parser.ExternalEntityRefHandler = self.defused_external_entity_ref_handler
+
+
+def create_parser(*args, **kwargs):
+    return DefusedExpatParser(*args, **kwargs)
diff --git a/python/defusedxml/lxml.py b/python/defusedxml/lxml.py
new file mode 100644
index 0000000..7f3ee0b
--- /dev/null
+++ b/python/defusedxml/lxml.py
@@ -0,0 +1,153 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Example code for lxml.etree protection
+
+The code has NO protection against decompression bombs.
+"""
+from __future__ import print_function, absolute_import
+
+import threading
+from lxml import etree as _etree
+
+from .common import DTDForbidden, EntitiesForbidden, NotSupportedError
+
+LXML3 = _etree.LXML_VERSION[0] >= 3
+
+__origin__ = "lxml.etree"
+
+tostring = _etree.tostring
+
+
+class RestrictedElement(_etree.ElementBase):
+    """A restricted Element class that filters out instances of some classes
+    """
+    __slots__ = ()
+    # blacklist = (etree._Entity, etree._ProcessingInstruction, etree._Comment)
+    blacklist = _etree._Entity
+
+    def _filter(self, iterator):
+        blacklist = self.blacklist
+        for child in iterator:
+            if isinstance(child, blacklist):
+                continue
+            yield child
+
+    def __iter__(self):
+        iterator = super(RestrictedElement, self).__iter__()
+        return self._filter(iterator)
+
+    def iterchildren(self, tag=None, reversed=False):
+        iterator = super(RestrictedElement, self).iterchildren(
+            tag=tag, reversed=reversed)
+        return self._filter(iterator)
+
+    def iter(self, tag=None, *tags):
+        iterator = super(RestrictedElement, self).iter(tag=tag, *tags)
+        return self._filter(iterator)
+
+    def iterdescendants(self, tag=None, *tags):
+        iterator = super(RestrictedElement,
+                         self).iterdescendants(tag=tag, *tags)
+        return self._filter(iterator)
+
+    def itersiblings(self, tag=None, preceding=False):
+        iterator = super(RestrictedElement, self).itersiblings(
+            tag=tag, preceding=preceding)
+        return self._filter(iterator)
+
+    def getchildren(self):
+        iterator = super(RestrictedElement, self).__iter__()
+        return list(self._filter(iterator))
+
+    def getiterator(self, tag=None):
+        iterator = super(RestrictedElement, self).getiterator(tag)
+        return self._filter(iterator)
+
+
+class GlobalParserTLS(threading.local):
+    """Thread local context for custom parser instances
+    """
+    parser_config = {
+        'resolve_entities': False,
+        # 'remove_comments': True,
+        # 'remove_pis': True,
+    }
+
+    element_class = RestrictedElement
+
+    def createDefaultParser(self):
+        parser = _etree.XMLParser(**self.parser_config)
+        element_class = self.element_class
+        if self.element_class is not None:
+            lookup = _etree.ElementDefaultClassLookup(element=element_class)
+            parser.set_element_class_lookup(lookup)
+        return parser
+
+    def setDefaultParser(self, parser):
+        self._default_parser = parser
+
+    def getDefaultParser(self):
+        parser = getattr(self, "_default_parser", None)
+        if parser is None:
+            parser = self.createDefaultParser()
+            self.setDefaultParser(parser)
+        return parser
+
+
+_parser_tls = GlobalParserTLS()
+getDefaultParser = _parser_tls.getDefaultParser
+
+
+def check_docinfo(elementtree, forbid_dtd=False, forbid_entities=True):
+    """Check docinfo of an element tree for DTD and entity declarations
+
+    The check for entity declarations needs lxml 3 or newer. lxml 2.x does
+    not support dtd.iterentities().
+    """
+    docinfo = elementtree.docinfo
+    if docinfo.doctype:
+        if forbid_dtd:
+            raise DTDForbidden(docinfo.doctype,
+                               docinfo.system_url,
+                               docinfo.public_id)
+        if forbid_entities and not LXML3:
+            # lxml < 3 has no iterentities()
+            raise NotSupportedError("Unable to check for entity declarations "
+                                    "in lxml 2.x")
+
+    if forbid_entities:
+        for dtd in docinfo.internalDTD, docinfo.externalDTD:
+            if dtd is None:
+                continue
+            for entity in dtd.iterentities():
+                raise EntitiesForbidden(entity.name, entity.content, None,
+                                        None, None, None)
+
+
+def parse(source, parser=None, base_url=None, forbid_dtd=False,
+          forbid_entities=True):
+    if parser is None:
+        parser = getDefaultParser()
+    elementtree = _etree.parse(source, parser, base_url=base_url)
+    check_docinfo(elementtree, forbid_dtd, forbid_entities)
+    return elementtree
+
+
+def fromstring(text, parser=None, base_url=None, forbid_dtd=False,
+               forbid_entities=True):
+    if parser is None:
+        parser = getDefaultParser()
+    rootelement = _etree.fromstring(text, parser, base_url=base_url)
+    elementtree = rootelement.getroottree()
+    check_docinfo(elementtree, forbid_dtd, forbid_entities)
+    return rootelement
+
+
+XML = fromstring
+
+
+def iterparse(*args, **kwargs):
+    raise NotSupportedError("defused lxml.etree.iterparse not available")
diff --git a/python/defusedxml/minidom.py b/python/defusedxml/minidom.py
new file mode 100644
index 0000000..0fd8684
--- /dev/null
+++ b/python/defusedxml/minidom.py
@@ -0,0 +1,42 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.dom.minidom
+"""
+from __future__ import print_function, absolute_import
+
+from xml.dom.minidom import _do_pulldom_parse
+from . import expatbuilder as _expatbuilder
+from . import pulldom as _pulldom
+
+__origin__ = "xml.dom.minidom"
+
+
+def parse(file, parser=None, bufsize=None, forbid_dtd=False,
+          forbid_entities=True, forbid_external=True):
+    """Parse a file into a DOM by filename or file object."""
+    if parser is None and not bufsize:
+        return _expatbuilder.parse(file, forbid_dtd=forbid_dtd,
+                                   forbid_entities=forbid_entities,
+                                   forbid_external=forbid_external)
+    else:
+        return _do_pulldom_parse(_pulldom.parse, (file,),
+                                 {'parser': parser, 'bufsize': bufsize,
+                                  'forbid_dtd': forbid_dtd, 'forbid_entities': forbid_entities,
+                                  'forbid_external': forbid_external})
+
+
+def parseString(string, parser=None, forbid_dtd=False,
+                forbid_entities=True, forbid_external=True):
+    """Parse a file into a DOM from a string."""
+    if parser is None:
+        return _expatbuilder.parseString(string, forbid_dtd=forbid_dtd,
+                                         forbid_entities=forbid_entities,
+                                         forbid_external=forbid_external)
+    else:
+        return _do_pulldom_parse(_pulldom.parseString, (string,),
+                                 {'parser': parser, 'forbid_dtd': forbid_dtd,
+                                  'forbid_entities': forbid_entities,
+                                  'forbid_external': forbid_external})
diff --git a/python/defusedxml/pulldom.py b/python/defusedxml/pulldom.py
new file mode 100644
index 0000000..fc9e466
--- /dev/null
+++ b/python/defusedxml/pulldom.py
@@ -0,0 +1,34 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.dom.pulldom
+"""
+from __future__ import print_function, absolute_import
+
+from xml.dom.pulldom import parse as _parse
+from xml.dom.pulldom import parseString as _parseString
+from .sax import make_parser
+
+__origin__ = "xml.dom.pulldom"
+
+
+def parse(stream_or_string, parser=None, bufsize=None, forbid_dtd=False,
+          forbid_entities=True, forbid_external=True):
+    if parser is None:
+        parser = make_parser()
+        parser.forbid_dtd = forbid_dtd
+        parser.forbid_entities = forbid_entities
+        parser.forbid_external = forbid_external
+    return _parse(stream_or_string, parser, bufsize)
+
+
+def parseString(string, parser=None, forbid_dtd=False,
+                forbid_entities=True, forbid_external=True):
+    if parser is None:
+        parser = make_parser()
+        parser.forbid_dtd = forbid_dtd
+        parser.forbid_entities = forbid_entities
+        parser.forbid_external = forbid_external
+    return _parseString(string, parser)
diff --git a/python/defusedxml/sax.py b/python/defusedxml/sax.py
new file mode 100644
index 0000000..534d0ca
--- /dev/null
+++ b/python/defusedxml/sax.py
@@ -0,0 +1,49 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xml.sax
+"""
+from __future__ import print_function, absolute_import
+
+from xml.sax import InputSource as _InputSource
+from xml.sax import ErrorHandler as _ErrorHandler
+
+from . import expatreader
+
+__origin__ = "xml.sax"
+
+
+def parse(source, handler, errorHandler=_ErrorHandler(), forbid_dtd=False,
+          forbid_entities=True, forbid_external=True):
+    parser = make_parser()
+    parser.setContentHandler(handler)
+    parser.setErrorHandler(errorHandler)
+    parser.forbid_dtd = forbid_dtd
+    parser.forbid_entities = forbid_entities
+    parser.forbid_external = forbid_external
+    parser.parse(source)
+
+
+def parseString(string, handler, errorHandler=_ErrorHandler(),
+                forbid_dtd=False, forbid_entities=True,
+                forbid_external=True):
+    from io import BytesIO
+
+    if errorHandler is None:
+        errorHandler = _ErrorHandler()
+    parser = make_parser()
+    parser.setContentHandler(handler)
+    parser.setErrorHandler(errorHandler)
+    parser.forbid_dtd = forbid_dtd
+    parser.forbid_entities = forbid_entities
+    parser.forbid_external = forbid_external
+
+    inpsrc = _InputSource()
+    inpsrc.setByteStream(BytesIO(string))
+    parser.parse(inpsrc)
+
+
+def make_parser(parser_list=[]):
+    return expatreader.create_parser()
diff --git a/python/defusedxml/xmlrpc.py b/python/defusedxml/xmlrpc.py
new file mode 100644
index 0000000..2a456e6
--- /dev/null
+++ b/python/defusedxml/xmlrpc.py
@@ -0,0 +1,157 @@
+# defusedxml
+#
+# Copyright (c) 2013 by Christian Heimes <christian@python.org>
+# Licensed to PSF under a Contributor Agreement.
+# See http://www.python.org/psf/license for licensing details.
+"""Defused xmlrpclib
+
+Also defuses gzip bomb
+"""
+from __future__ import print_function, absolute_import
+
+import io
+
+from .common import (
+    DTDForbidden, EntitiesForbidden, ExternalReferenceForbidden, PY3)
+
+if PY3:
+    __origin__ = "xmlrpc.client"
+    from xmlrpc.client import ExpatParser
+    from xmlrpc import client as xmlrpc_client
+    from xmlrpc import server as xmlrpc_server
+    from xmlrpc.client import gzip_decode as _orig_gzip_decode
+    from xmlrpc.client import GzipDecodedResponse as _OrigGzipDecodedResponse
+else:
+    __origin__ = "xmlrpclib"
+    from xmlrpclib import ExpatParser
+    import xmlrpclib as xmlrpc_client
+    xmlrpc_server = None
+    from xmlrpclib import gzip_decode as _orig_gzip_decode
+    from xmlrpclib import GzipDecodedResponse as _OrigGzipDecodedResponse
+
+try:
+    import gzip
+except ImportError:
+    gzip = None
+
+
+# Limit maximum request size to prevent resource exhaustion DoS
+# Also used to limit maximum amount of gzip decoded data in order to prevent
+# decompression bombs
+# A value of -1 or smaller disables the limit
+MAX_DATA = 30 * 1024 * 1024  # 30 MB
+
+
+def defused_gzip_decode(data, limit=None):
+    """gzip encoded data -> unencoded data
+
+    Decode data using the gzip content encoding as described in RFC 1952
+    """
+    if not gzip:
+        raise NotImplementedError
+    if limit is None:
+        limit = MAX_DATA
+    f = io.BytesIO(data)
+    gzf = gzip.GzipFile(mode="rb", fileobj=f)
+    try:
+        if limit < 0:  # no limit
+            decoded = gzf.read()
+        else:
+            decoded = gzf.read(limit + 1)
+    except IOError:
+        raise ValueError("invalid data")
+    f.close()
+    gzf.close()
+    if limit >= 0 and len(decoded) > limit:
+        raise ValueError("max gzipped payload length exceeded")
+    return decoded
+
+
+class DefusedGzipDecodedResponse(gzip.GzipFile if gzip else object):
+    """a file-like object to decode a response encoded with the gzip
+    method, as described in RFC 1952.
+    """
+
+    def __init__(self, response, limit=None):
+        # response doesn't support tell() and read(), required by
+        # GzipFile
+        if not gzip:
+            raise NotImplementedError
+        self.limit = limit = limit if limit is not None else MAX_DATA
+        if limit < 0:  # no limit
+            data = response.read()
+            self.readlength = None
+        else:
+            data = response.read(limit + 1)
+            self.readlength = 0
+        if limit >= 0 and len(data) > limit:
+            raise ValueError("max payload length exceeded")
+        self.stringio = io.BytesIO(data)
+        gzip.GzipFile.__init__(self, mode="rb", fileobj=self.stringio)
+
+    def read(self, n):
+        if self.limit >= 0:
+            left = self.limit - self.readlength
+            n = min(n, left + 1)
+            data = gzip.GzipFile.read(self, n)
+            self.readlength += len(data)
+            if self.readlength > self.limit:
+                raise ValueError("max payload length exceeded")
+            return data
+        else:
+            return gzip.GzipFile.read(self, n)
+
+    def close(self):
+        gzip.GzipFile.close(self)
+        self.stringio.close()
+
+
+class DefusedExpatParser(ExpatParser):
+
+    def __init__(self, target, forbid_dtd=False, forbid_entities=True,
+                 forbid_external=True):
+        ExpatParser.__init__(self, target)
+        self.forbid_dtd = forbid_dtd
+        self.forbid_entities = forbid_entities
+        self.forbid_external = forbid_external
+        parser = self._parser
+        if self.forbid_dtd:
+            parser.StartDoctypeDeclHandler = self.defused_start_doctype_decl
+        if self.forbid_entities:
+            parser.EntityDeclHandler = self.defused_entity_decl
+            parser.UnparsedEntityDeclHandler = self.defused_unparsed_entity_decl
+        if self.forbid_external:
+            parser.ExternalEntityRefHandler = self.defused_external_entity_ref_handler
+
+    def defused_start_doctype_decl(self, name, sysid, pubid,
+                                   has_internal_subset):
+        raise DTDForbidden(name, sysid, pubid)
+
+    def defused_entity_decl(self, name, is_parameter_entity, value, base,
+                            sysid, pubid, notation_name):
+        raise EntitiesForbidden(name, value, base, sysid, pubid, notation_name)
+
+    def defused_unparsed_entity_decl(self, name, base, sysid, pubid,
+                                     notation_name):
+        # expat 1.2
+        raise EntitiesForbidden(name, None, base, sysid, pubid, notation_name)
+
+    def defused_external_entity_ref_handler(self, context, base, sysid,
+                                            pubid):
+        raise ExternalReferenceForbidden(context, base, sysid, pubid)
+
+
+def monkey_patch():
+    xmlrpc_client.FastParser = DefusedExpatParser
+    xmlrpc_client.GzipDecodedResponse = DefusedGzipDecodedResponse
+    xmlrpc_client.gzip_decode = defused_gzip_decode
+    if xmlrpc_server:
+        xmlrpc_server.gzip_decode = defused_gzip_decode
+
+
+def unmonkey_patch():
+    xmlrpc_client.FastParser = None
+    xmlrpc_client.GzipDecodedResponse = _OrigGzipDecodedResponse
+    xmlrpc_client.gzip_decode = _orig_gzip_decode
+    if xmlrpc_server:
+        xmlrpc_server.gzip_decode = _orig_gzip_decode
diff --git a/python/six.py b/python/six.py
new file mode 100644
index 0000000..6bf4fd3
--- /dev/null
+++ b/python/six.py
@@ -0,0 +1,891 @@
+# Copyright (c) 2010-2017 Benjamin Peterson
+#
+# Permission is hereby granted, free of charge, to any person obtaining a copy
+# of this software and associated documentation files (the "Software"), to deal
+# in the Software without restriction, including without limitation the rights
+# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+# copies of the Software, and to permit persons to whom the Software is
+# furnished to do so, subject to the following conditions:
+#
+# The above copyright notice and this permission notice shall be included in all
+# copies or substantial portions of the Software.
+#
+# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+# AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+# OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+# SOFTWARE.
+
+"""Utilities for writing code that runs on Python 2 and 3"""
+
+from __future__ import absolute_import
+
+import functools
+import itertools
+import operator
+import sys
+import types
+
+__author__ = "Benjamin Peterson <benjamin@python.org>"
+__version__ = "1.11.0"
+
+
+# Useful for very coarse version differentiation.
+PY2 = sys.version_info[0] == 2
+PY3 = sys.version_info[0] == 3
+PY34 = sys.version_info[0:2] >= (3, 4)
+
+if PY3:
+    string_types = str,
+    integer_types = int,
+    class_types = type,
+    text_type = str
+    binary_type = bytes
+
+    MAXSIZE = sys.maxsize
+else:
+    string_types = basestring,
+    integer_types = (int, long)
+    class_types = (type, types.ClassType)
+    text_type = unicode
+    binary_type = str
+
+    if sys.platform.startswith("java"):
+        # Jython always uses 32 bits.
+        MAXSIZE = int((1 << 31) - 1)
+    else:
+        # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
+        class X(object):
+
+            def __len__(self):
+                return 1 << 31
+        try:
+            len(X())
+        except OverflowError:
+            # 32-bit
+            MAXSIZE = int((1 << 31) - 1)
+        else:
+            # 64-bit
+            MAXSIZE = int((1 << 63) - 1)
+        del X
+
+
+def _add_doc(func, doc):
+    """Add documentation to a function."""
+    func.__doc__ = doc
+
+
+def _import_module(name):
+    """Import module, returning the module after the last dot."""
+    __import__(name)
+    return sys.modules[name]
+
+
+class _LazyDescr(object):
+
+    def __init__(self, name):
+        self.name = name
+
+    def __get__(self, obj, tp):
+        result = self._resolve()
+        setattr(obj, self.name, result)  # Invokes __set__.
+        try:
+            # This is a bit ugly, but it avoids running this again by
+            # removing this descriptor.
+            delattr(obj.__class__, self.name)
+        except AttributeError:
+            pass
+        return result
+
+
+class MovedModule(_LazyDescr):
+
+    def __init__(self, name, old, new=None):
+        super(MovedModule, self).__init__(name)
+        if PY3:
+            if new is None:
+                new = name
+            self.mod = new
+        else:
+            self.mod = old
+
+    def _resolve(self):
+        return _import_module(self.mod)
+
+    def __getattr__(self, attr):
+        _module = self._resolve()
+        value = getattr(_module, attr)
+        setattr(self, attr, value)
+        return value
+
+
+class _LazyModule(types.ModuleType):
+
+    def __init__(self, name):
+        super(_LazyModule, self).__init__(name)
+        self.__doc__ = self.__class__.__doc__
+
+    def __dir__(self):
+        attrs = ["__doc__", "__name__"]
+        attrs += [attr.name for attr in self._moved_attributes]
+        return attrs
+
+    # Subclasses should override this
+    _moved_attributes = []
+
+
+class MovedAttribute(_LazyDescr):
+
+    def __init__(self, name, old_mod, new_mod, old_attr=None, new_attr=None):
+        super(MovedAttribute, self).__init__(name)
+        if PY3:
+            if new_mod is None:
+                new_mod = name
+            self.mod = new_mod
+            if new_attr is None:
+                if old_attr is None:
+                    new_attr = name
+                else:
+                    new_attr = old_attr
+            self.attr = new_attr
+        else:
+            self.mod = old_mod
+            if old_attr is None:
+                old_attr = name
+            self.attr = old_attr
+
+    def _resolve(self):
+        module = _import_module(self.mod)
+        return getattr(module, self.attr)
+
+
+class _SixMetaPathImporter(object):
+
+    """
+    A meta path importer to import six.moves and its submodules.
+
+    This class implements a PEP302 finder and loader. It should be compatible
+    with Python 2.5 and all existing versions of Python3
+    """
+
+    def __init__(self, six_module_name):
+        self.name = six_module_name
+        self.known_modules = {}
+
+    def _add_module(self, mod, *fullnames):
+        for fullname in fullnames:
+            self.known_modules[self.name + "." + fullname] = mod
+
+    def _get_module(self, fullname):
+        return self.known_modules[self.name + "." + fullname]
+
+    def find_module(self, fullname, path=None):
+        if fullname in self.known_modules:
+            return self
+        return None
+
+    def __get_module(self, fullname):
+        try:
+            return self.known_modules[fullname]
+        except KeyError:
+            raise ImportError("This loader does not know module " + fullname)
+
+    def load_module(self, fullname):
+        try:
+            # in case of a reload
+            return sys.modules[fullname]
+        except KeyError:
+            pass
+        mod = self.__get_module(fullname)
+        if isinstance(mod, MovedModule):
+            mod = mod._resolve()
+        else:
+            mod.__loader__ = self
+        sys.modules[fullname] = mod
+        return mod
+
+    def is_package(self, fullname):
+        """
+        Return true, if the named module is a package.
+
+        We need this method to get correct spec objects with
+        Python 3.4 (see PEP451)
+        """
+        return hasattr(self.__get_module(fullname), "__path__")
+
+    def get_code(self, fullname):
+        """Return None
+
+        Required, if is_package is implemented"""
+        self.__get_module(fullname)  # eventually raises ImportError
+        return None
+    get_source = get_code  # same as get_code
+
+_importer = _SixMetaPathImporter(__name__)
+
+
+class _MovedItems(_LazyModule):
+
+    """Lazy loading of moved objects"""
+    __path__ = []  # mark as package
+
+
+_moved_attributes = [
+    MovedAttribute("cStringIO", "cStringIO", "io", "StringIO"),
+    MovedAttribute("filter", "itertools", "builtins", "ifilter", "filter"),
+    MovedAttribute("filterfalse", "itertools", "itertools", "ifilterfalse", "filterfalse"),
+    MovedAttribute("input", "__builtin__", "builtins", "raw_input", "input"),
+    MovedAttribute("intern", "__builtin__", "sys"),
+    MovedAttribute("map", "itertools", "builtins", "imap", "map"),
+    MovedAttribute("getcwd", "os", "os", "getcwdu", "getcwd"),
+    MovedAttribute("getcwdb", "os", "os", "getcwd", "getcwdb"),
+    MovedAttribute("getoutput", "commands", "subprocess"),
+    MovedAttribute("range", "__builtin__", "builtins", "xrange", "range"),
+    MovedAttribute("reload_module", "__builtin__", "importlib" if PY34 else "imp", "reload"),
+    MovedAttribute("reduce", "__builtin__", "functools"),
+    MovedAttribute("shlex_quote", "pipes", "shlex", "quote"),
+    MovedAttribute("StringIO", "StringIO", "io"),
+    MovedAttribute("UserDict", "UserDict", "collections"),
+    MovedAttribute("UserList", "UserList", "collections"),
+    MovedAttribute("UserString", "UserString", "collections"),
+    MovedAttribute("xrange", "__builtin__", "builtins", "xrange", "range"),
+    MovedAttribute("zip", "itertools", "builtins", "izip", "zip"),
+    MovedAttribute("zip_longest", "itertools", "itertools", "izip_longest", "zip_longest"),
+    MovedModule("builtins", "__builtin__"),
+    MovedModule("configparser", "ConfigParser"),
+    MovedModule("copyreg", "copy_reg"),
+    MovedModule("dbm_gnu", "gdbm", "dbm.gnu"),
+    MovedModule("_dummy_thread", "dummy_thread", "_dummy_thread"),
+    MovedModule("http_cookiejar", "cookielib", "http.cookiejar"),
+    MovedModule("http_cookies", "Cookie", "http.cookies"),
+    MovedModule("html_entities", "htmlentitydefs", "html.entities"),
+    MovedModule("html_parser", "HTMLParser", "html.parser"),
+    MovedModule("http_client", "httplib", "http.client"),
+    MovedModule("email_mime_base", "email.MIMEBase", "email.mime.base"),
+    MovedModule("email_mime_image", "email.MIMEImage", "email.mime.image"),
+    MovedModule("email_mime_multipart", "email.MIMEMultipart", "email.mime.multipart"),
+    MovedModule("email_mime_nonmultipart", "email.MIMENonMultipart", "email.mime.nonmultipart"),
+    MovedModule("email_mime_text", "email.MIMEText", "email.mime.text"),
+    MovedModule("BaseHTTPServer", "BaseHTTPServer", "http.server"),
+    MovedModule("CGIHTTPServer", "CGIHTTPServer", "http.server"),
+    MovedModule("SimpleHTTPServer", "SimpleHTTPServer", "http.server"),
+    MovedModule("cPickle", "cPickle", "pickle"),
+    MovedModule("queue", "Queue"),
+    MovedModule("reprlib", "repr"),
+    MovedModule("socketserver", "SocketServer"),
+    MovedModule("_thread", "thread", "_thread"),
+    MovedModule("tkinter", "Tkinter"),
+    MovedModule("tkinter_dialog", "Dialog", "tkinter.dialog"),
+    MovedModule("tkinter_filedialog", "FileDialog", "tkinter.filedialog"),
+    MovedModule("tkinter_scrolledtext", "ScrolledText", "tkinter.scrolledtext"),
+    MovedModule("tkinter_simpledialog", "SimpleDialog", "tkinter.simpledialog"),
+    MovedModule("tkinter_tix", "Tix", "tkinter.tix"),
+    MovedModule("tkinter_ttk", "ttk", "tkinter.ttk"),
+    MovedModule("tkinter_constants", "Tkconstants", "tkinter.constants"),
+    MovedModule("tkinter_dnd", "Tkdnd", "tkinter.dnd"),
+    MovedModule("tkinter_colorchooser", "tkColorChooser",
+                "tkinter.colorchooser"),
+    MovedModule("tkinter_commondialog", "tkCommonDialog",
+                "tkinter.commondialog"),
+    MovedModule("tkinter_tkfiledialog", "tkFileDialog", "tkinter.filedialog"),
+    MovedModule("tkinter_font", "tkFont", "tkinter.font"),
+    MovedModule("tkinter_messagebox", "tkMessageBox", "tkinter.messagebox"),
+    MovedModule("tkinter_tksimpledialog", "tkSimpleDialog",
+                "tkinter.simpledialog"),
+    MovedModule("urllib_parse", __name__ + ".moves.urllib_parse", "urllib.parse"),
+    MovedModule("urllib_error", __name__ + ".moves.urllib_error", "urllib.error"),
+    MovedModule("urllib", __name__ + ".moves.urllib", __name__ + ".moves.urllib"),
+    MovedModule("urllib_robotparser", "robotparser", "urllib.robotparser"),
+    MovedModule("xmlrpc_client", "xmlrpclib", "xmlrpc.client"),
+    MovedModule("xmlrpc_server", "SimpleXMLRPCServer", "xmlrpc.server"),
+]
+# Add windows specific modules.
+if sys.platform == "win32":
+    _moved_attributes += [
+        MovedModule("winreg", "_winreg"),
+    ]
+
+for attr in _moved_attributes:
+    setattr(_MovedItems, attr.name, attr)
+    if isinstance(attr, MovedModule):
+        _importer._add_module(attr, "moves." + attr.name)
+del attr
+
+_MovedItems._moved_attributes = _moved_attributes
+
+moves = _MovedItems(__name__ + ".moves")
+_importer._add_module(moves, "moves")
+
+
+class Module_six_moves_urllib_parse(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_parse"""
+
+
+_urllib_parse_moved_attributes = [
+    MovedAttribute("ParseResult", "urlparse", "urllib.parse"),
+    MovedAttribute("SplitResult", "urlparse", "urllib.parse"),
+    MovedAttribute("parse_qs", "urlparse", "urllib.parse"),
+    MovedAttribute("parse_qsl", "urlparse", "urllib.parse"),
+    MovedAttribute("urldefrag", "urlparse", "urllib.parse"),
+    MovedAttribute("urljoin", "urlparse", "urllib.parse"),
+    MovedAttribute("urlparse", "urlparse", "urllib.parse"),
+    MovedAttribute("urlsplit", "urlparse", "urllib.parse"),
+    MovedAttribute("urlunparse", "urlparse", "urllib.parse"),
+    MovedAttribute("urlunsplit", "urlparse", "urllib.parse"),
+    MovedAttribute("quote", "urllib", "urllib.parse"),
+    MovedAttribute("quote_plus", "urllib", "urllib.parse"),
+    MovedAttribute("unquote", "urllib", "urllib.parse"),
+    MovedAttribute("unquote_plus", "urllib", "urllib.parse"),
+    MovedAttribute("unquote_to_bytes", "urllib", "urllib.parse", "unquote", "unquote_to_bytes"),
+    MovedAttribute("urlencode", "urllib", "urllib.parse"),
+    MovedAttribute("splitquery", "urllib", "urllib.parse"),
+    MovedAttribute("splittag", "urllib", "urllib.parse"),
+    MovedAttribute("splituser", "urllib", "urllib.parse"),
+    MovedAttribute("splitvalue", "urllib", "urllib.parse"),
+    MovedAttribute("uses_fragment", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_netloc", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_params", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_query", "urlparse", "urllib.parse"),
+    MovedAttribute("uses_relative", "urlparse", "urllib.parse"),
+]
+for attr in _urllib_parse_moved_attributes:
+    setattr(Module_six_moves_urllib_parse, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_parse._moved_attributes = _urllib_parse_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_parse(__name__ + ".moves.urllib_parse"),
+                      "moves.urllib_parse", "moves.urllib.parse")
+
+
+class Module_six_moves_urllib_error(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_error"""
+
+
+_urllib_error_moved_attributes = [
+    MovedAttribute("URLError", "urllib2", "urllib.error"),
+    MovedAttribute("HTTPError", "urllib2", "urllib.error"),
+    MovedAttribute("ContentTooShortError", "urllib", "urllib.error"),
+]
+for attr in _urllib_error_moved_attributes:
+    setattr(Module_six_moves_urllib_error, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_error._moved_attributes = _urllib_error_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_error(__name__ + ".moves.urllib.error"),
+                      "moves.urllib_error", "moves.urllib.error")
+
+
+class Module_six_moves_urllib_request(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_request"""
+
+
+_urllib_request_moved_attributes = [
+    MovedAttribute("urlopen", "urllib2", "urllib.request"),
+    MovedAttribute("install_opener", "urllib2", "urllib.request"),
+    MovedAttribute("build_opener", "urllib2", "urllib.request"),
+    MovedAttribute("pathname2url", "urllib", "urllib.request"),
+    MovedAttribute("url2pathname", "urllib", "urllib.request"),
+    MovedAttribute("getproxies", "urllib", "urllib.request"),
+    MovedAttribute("Request", "urllib2", "urllib.request"),
+    MovedAttribute("OpenerDirector", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPDefaultErrorHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPRedirectHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPCookieProcessor", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyHandler", "urllib2", "urllib.request"),
+    MovedAttribute("BaseHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPPasswordMgr", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPPasswordMgrWithDefaultRealm", "urllib2", "urllib.request"),
+    MovedAttribute("AbstractBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyBasicAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("AbstractDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("ProxyDigestAuthHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPSHandler", "urllib2", "urllib.request"),
+    MovedAttribute("FileHandler", "urllib2", "urllib.request"),
+    MovedAttribute("FTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("CacheFTPHandler", "urllib2", "urllib.request"),
+    MovedAttribute("UnknownHandler", "urllib2", "urllib.request"),
+    MovedAttribute("HTTPErrorProcessor", "urllib2", "urllib.request"),
+    MovedAttribute("urlretrieve", "urllib", "urllib.request"),
+    MovedAttribute("urlcleanup", "urllib", "urllib.request"),
+    MovedAttribute("URLopener", "urllib", "urllib.request"),
+    MovedAttribute("FancyURLopener", "urllib", "urllib.request"),
+    MovedAttribute("proxy_bypass", "urllib", "urllib.request"),
+    MovedAttribute("parse_http_list", "urllib2", "urllib.request"),
+    MovedAttribute("parse_keqv_list", "urllib2", "urllib.request"),
+]
+for attr in _urllib_request_moved_attributes:
+    setattr(Module_six_moves_urllib_request, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_request._moved_attributes = _urllib_request_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_request(__name__ + ".moves.urllib.request"),
+                      "moves.urllib_request", "moves.urllib.request")
+
+
+class Module_six_moves_urllib_response(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_response"""
+
+
+_urllib_response_moved_attributes = [
+    MovedAttribute("addbase", "urllib", "urllib.response"),
+    MovedAttribute("addclosehook", "urllib", "urllib.response"),
+    MovedAttribute("addinfo", "urllib", "urllib.response"),
+    MovedAttribute("addinfourl", "urllib", "urllib.response"),
+]
+for attr in _urllib_response_moved_attributes:
+    setattr(Module_six_moves_urllib_response, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_response._moved_attributes = _urllib_response_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_response(__name__ + ".moves.urllib.response"),
+                      "moves.urllib_response", "moves.urllib.response")
+
+
+class Module_six_moves_urllib_robotparser(_LazyModule):
+
+    """Lazy loading of moved objects in six.moves.urllib_robotparser"""
+
+
+_urllib_robotparser_moved_attributes = [
+    MovedAttribute("RobotFileParser", "robotparser", "urllib.robotparser"),
+]
+for attr in _urllib_robotparser_moved_attributes:
+    setattr(Module_six_moves_urllib_robotparser, attr.name, attr)
+del attr
+
+Module_six_moves_urllib_robotparser._moved_attributes = _urllib_robotparser_moved_attributes
+
+_importer._add_module(Module_six_moves_urllib_robotparser(__name__ + ".moves.urllib.robotparser"),
+                      "moves.urllib_robotparser", "moves.urllib.robotparser")
+
+
+class Module_six_moves_urllib(types.ModuleType):
+
+    """Create a six.moves.urllib namespace that resembles the Python 3 namespace"""
+    __path__ = []  # mark as package
+    parse = _importer._get_module("moves.urllib_parse")
+    error = _importer._get_module("moves.urllib_error")
+    request = _importer._get_module("moves.urllib_request")
+    response = _importer._get_module("moves.urllib_response")
+    robotparser = _importer._get_module("moves.urllib_robotparser")
+
+    def __dir__(self):
+        return ['parse', 'error', 'request', 'response', 'robotparser']
+
+_importer._add_module(Module_six_moves_urllib(__name__ + ".moves.urllib"),
+                      "moves.urllib")
+
+
+def add_move(move):
+    """Add an item to six.moves."""
+    setattr(_MovedItems, move.name, move)
+
+
+def remove_move(name):
+    """Remove item from six.moves."""
+    try:
+        delattr(_MovedItems, name)
+    except AttributeError:
+        try:
+            del moves.__dict__[name]
+        except KeyError:
+            raise AttributeError("no such move, %r" % (name,))
+
+
+if PY3:
+    _meth_func = "__func__"
+    _meth_self = "__self__"
+
+    _func_closure = "__closure__"
+    _func_code = "__code__"
+    _func_defaults = "__defaults__"
+    _func_globals = "__globals__"
+else:
+    _meth_func = "im_func"
+    _meth_self = "im_self"
+
+    _func_closure = "func_closure"
+    _func_code = "func_code"
+    _func_defaults = "func_defaults"
+    _func_globals = "func_globals"
+
+
+try:
+    advance_iterator = next
+except NameError:
+    def advance_iterator(it):
+        return it.next()
+next = advance_iterator
+
+
+try:
+    callable = callable
+except NameError:
+    def callable(obj):
+        return any("__call__" in klass.__dict__ for klass in type(obj).__mro__)
+
+
+if PY3:
+    def get_unbound_function(unbound):
+        return unbound
+
+    create_bound_method = types.MethodType
+
+    def create_unbound_method(func, cls):
+        return func
+
+    Iterator = object
+else:
+    def get_unbound_function(unbound):
+        return unbound.im_func
+
+    def create_bound_method(func, obj):
+        return types.MethodType(func, obj, obj.__class__)
+
+    def create_unbound_method(func, cls):
+        return types.MethodType(func, None, cls)
+
+    class Iterator(object):
+
+        def next(self):
+            return type(self).__next__(self)
+
+    callable = callable
+_add_doc(get_unbound_function,
+         """Get the function out of a possibly unbound function""")
+
+
+get_method_function = operator.attrgetter(_meth_func)
+get_method_self = operator.attrgetter(_meth_self)
+get_function_closure = operator.attrgetter(_func_closure)
+get_function_code = operator.attrgetter(_func_code)
+get_function_defaults = operator.attrgetter(_func_defaults)
+get_function_globals = operator.attrgetter(_func_globals)
+
+
+if PY3:
+    def iterkeys(d, **kw):
+        return iter(d.keys(**kw))
+
+    def itervalues(d, **kw):
+        return iter(d.values(**kw))
+
+    def iteritems(d, **kw):
+        return iter(d.items(**kw))
+
+    def iterlists(d, **kw):
+        return iter(d.lists(**kw))
+
+    viewkeys = operator.methodcaller("keys")
+
+    viewvalues = operator.methodcaller("values")
+
+    viewitems = operator.methodcaller("items")
+else:
+    def iterkeys(d, **kw):
+        return d.iterkeys(**kw)
+
+    def itervalues(d, **kw):
+        return d.itervalues(**kw)
+
+    def iteritems(d, **kw):
+        return d.iteritems(**kw)
+
+    def iterlists(d, **kw):
+        return d.iterlists(**kw)
+
+    viewkeys = operator.methodcaller("viewkeys")
+
+    viewvalues = operator.methodcaller("viewvalues")
+
+    viewitems = operator.methodcaller("viewitems")
+
+_add_doc(iterkeys, "Return an iterator over the keys of a dictionary.")
+_add_doc(itervalues, "Return an iterator over the values of a dictionary.")
+_add_doc(iteritems,
+         "Return an iterator over the (key, value) pairs of a dictionary.")
+_add_doc(iterlists,
+         "Return an iterator over the (key, [values]) pairs of a dictionary.")
+
+
+if PY3:
+    def b(s):
+        return s.encode("latin-1")
+
+    def u(s):
+        return s
+    unichr = chr
+    import struct
+    int2byte = struct.Struct(">B").pack
+    del struct
+    byte2int = operator.itemgetter(0)
+    indexbytes = operator.getitem
+    iterbytes = iter
+    import io
+    StringIO = io.StringIO
+    BytesIO = io.BytesIO
+    _assertCountEqual = "assertCountEqual"
+    if sys.version_info[1] <= 1:
+        _assertRaisesRegex = "assertRaisesRegexp"
+        _assertRegex = "assertRegexpMatches"
+    else:
+        _assertRaisesRegex = "assertRaisesRegex"
+        _assertRegex = "assertRegex"
+else:
+    def b(s):
+        return s
+    # Workaround for standalone backslash
+
+    def u(s):
+        return unicode(s.replace(r'\\', r'\\\\'), "unicode_escape")
+    unichr = unichr
+    int2byte = chr
+
+    def byte2int(bs):
+        return ord(bs[0])
+
+    def indexbytes(buf, i):
+        return ord(buf[i])
+    iterbytes = functools.partial(itertools.imap, ord)
+    import StringIO
+    StringIO = BytesIO = StringIO.StringIO
+    _assertCountEqual = "assertItemsEqual"
+    _assertRaisesRegex = "assertRaisesRegexp"
+    _assertRegex = "assertRegexpMatches"
+_add_doc(b, """Byte literal""")
+_add_doc(u, """Text literal""")
+
+
+def assertCountEqual(self, *args, **kwargs):
+    return getattr(self, _assertCountEqual)(*args, **kwargs)
+
+
+def assertRaisesRegex(self, *args, **kwargs):
+    return getattr(self, _assertRaisesRegex)(*args, **kwargs)
+
+
+def assertRegex(self, *args, **kwargs):
+    return getattr(self, _assertRegex)(*args, **kwargs)
+
+
+if PY3:
+    exec_ = getattr(moves.builtins, "exec")
+
+    def reraise(tp, value, tb=None):
+        try:
+            if value is None:
+                value = tp()
+            if value.__traceback__ is not tb:
+                raise value.with_traceback(tb)
+            raise value
+        finally:
+            value = None
+            tb = None
+
+else:
+    def exec_(_code_, _globs_=None, _locs_=None):
+        """Execute code in a namespace."""
+        if _globs_ is None:
+            frame = sys._getframe(1)
+            _globs_ = frame.f_globals
+            if _locs_ is None:
+                _locs_ = frame.f_locals
+            del frame
+        elif _locs_ is None:
+            _locs_ = _globs_
+        exec("""exec _code_ in _globs_, _locs_""")
+
+    exec_("""def reraise(tp, value, tb=None):
+    try:
+        raise tp, value, tb
+    finally:
+        tb = None
+""")
+
+
+if sys.version_info[:2] == (3, 2):
+    exec_("""def raise_from(value, from_value):
+    try:
+        if from_value is None:
+            raise value
+        raise value from from_value
+    finally:
+        value = None
+""")
+elif sys.version_info[:2] > (3, 2):
+    exec_("""def raise_from(value, from_value):
+    try:
+        raise value from from_value
+    finally:
+        value = None
+""")
+else:
+    def raise_from(value, from_value):
+        raise value
+
+
+print_ = getattr(moves.builtins, "print", None)
+if print_ is None:
+    def print_(*args, **kwargs):
+        """The new-style print function for Python 2.4 and 2.5."""
+        fp = kwargs.pop("file", sys.stdout)
+        if fp is None:
+            return
+
+        def write(data):
+            if not isinstance(data, basestring):
+                data = str(data)
+            # If the file has an encoding, encode unicode with it.
+            if (isinstance(fp, file) and
+                    isinstance(data, unicode) and
+                    fp.encoding is not None):
+                errors = getattr(fp, "errors", None)
+                if errors is None:
+                    errors = "strict"
+                data = data.encode(fp.encoding, errors)
+            fp.write(data)
+        want_unicode = False
+        sep = kwargs.pop("sep", None)
+        if sep is not None:
+            if isinstance(sep, unicode):
+                want_unicode = True
+            elif not isinstance(sep, str):
+                raise TypeError("sep must be None or a string")
+        end = kwargs.pop("end", None)
+        if end is not None:
+            if isinstance(end, unicode):
+                want_unicode = True
+            elif not isinstance(end, str):
+                raise TypeError("end must be None or a string")
+        if kwargs:
+            raise TypeError("invalid keyword arguments to print()")
+        if not want_unicode:
+            for arg in args:
+                if isinstance(arg, unicode):
+                    want_unicode = True
+                    break
+        if want_unicode:
+            newline = unicode("\n")
+            space = unicode(" ")
+        else:
+            newline = "\n"
+            space = " "
+        if sep is None:
+            sep = space
+        if end is None:
+            end = newline
+        for i, arg in enumerate(args):
+            if i:
+                write(sep)
+            write(arg)
+        write(end)
+if sys.version_info[:2] < (3, 3):
+    _print = print_
+
+    def print_(*args, **kwargs):
+        fp = kwargs.get("file", sys.stdout)
+        flush = kwargs.pop("flush", False)
+        _print(*args, **kwargs)
+        if flush and fp is not None:
+            fp.flush()
+
+_add_doc(reraise, """Reraise an exception.""")
+
+if sys.version_info[0:2] < (3, 4):
+    def wraps(wrapped, assigned=functools.WRAPPER_ASSIGNMENTS,
+              updated=functools.WRAPPER_UPDATES):
+        def wrapper(f):
+            f = functools.wraps(wrapped, assigned, updated)(f)
+            f.__wrapped__ = wrapped
+            return f
+        return wrapper
+else:
+    wraps = functools.wraps
+
+
+def with_metaclass(meta, *bases):
+    """Create a base class with a metaclass."""
+    # This requires a bit of explanation: the basic idea is to make a dummy
+    # metaclass for one level of class instantiation that replaces itself with
+    # the actual metaclass.
+    class metaclass(type):
+
+        def __new__(cls, name, this_bases, d):
+            return meta(name, bases, d)
+
+        @classmethod
+        def __prepare__(cls, name, this_bases):
+            return meta.__prepare__(name, bases)
+    return type.__new__(metaclass, 'temporary_class', (), {})
+
+
+def add_metaclass(metaclass):
+    """Class decorator for creating a class with a metaclass."""
+    def wrapper(cls):
+        orig_vars = cls.__dict__.copy()
+        slots = orig_vars.get('__slots__')
+        if slots is not None:
+            if isinstance(slots, str):
+                slots = [slots]
+            for slots_var in slots:
+                orig_vars.pop(slots_var)
+        orig_vars.pop('__dict__', None)
+        orig_vars.pop('__weakref__', None)
+        return metaclass(cls.__name__, cls.__bases__, orig_vars)
+    return wrapper
+
+
+def python_2_unicode_compatible(klass):
+    """
+    A decorator that defines __unicode__ and __str__ methods under Python 2.
+    Under Python 3 it does nothing.
+
+    To support Python 2 and 3 with a single code base, define a __str__ method
+    returning text and apply this decorator to the class.
+    """
+    if PY2:
+        if '__str__' not in klass.__dict__:
+            raise ValueError("@python_2_unicode_compatible cannot be applied "
+                             "to %s because it doesn't define __str__()." %
+                             klass.__name__)
+        klass.__unicode__ = klass.__str__
+        klass.__str__ = lambda self: self.__unicode__().encode('utf-8')
+    return klass
+
+
+# Complete the moves implementation.
+# This code is at the end of this module to speed up module loading.
+# Turn this module into a package.
+__path__ = []  # required for PEP 302 and PEP 451
+__package__ = __name__  # see PEP 366 @ReservedAssignment
+if globals().get("__spec__") is not None:
+    __spec__.submodule_search_locations = []  # PEP 451 @UndefinedVariable
+# Remove other six meta path importers, since they cause problems. This can
+# happen if six is removed from sys.modules and then reloaded. (Setuptools does
+# this for some reason.)
+if sys.meta_path:
+    for i, importer in enumerate(sys.meta_path):
+        # Here's some real nastiness: Another "instance" of the six module might
+        # be floating around. Therefore, we can't use isinstance() to check for
+        # the six meta path importer, since the other six instance will have
+        # inserted an importer with different class.
+        if (type(importer).__name__ == "_SixMetaPathImporter" and
+                importer.name == __name__):
+            del sys.meta_path[i]
+            break
+    del i, importer
+# Finally, add the importer to the meta path import hook.
+sys.meta_path.append(_importer)