bpo-40066: Enum: modify `repr()` and `str()` (GH-22392)

* Enum: streamline repr() and str(); improve docs

- repr() is now ``enum_class.member_name``
- stdlib global enums are ``module_name.member_name``
- str() is now ``member_name``
- add HOW-TO section for ``Enum``
- change main documentation to be an API reference

1 files changed, 441 insertions, 1197 deletions

diff --git a/Doc/library/enum.rst b/Doc/library/enum.rst
index 73b77cb..3a6b2aa 100644
--- a/Doc/library/enum.rst
+++ b/Doc/library/enum.rst
@@ -13,1368 +13,612 @@
 
 **Source code:** :source:`Lib/enum.py`
 
-----------------
-
-An enumeration is a set of symbolic names (members) bound to unique,
-constant values.  Within an enumeration, the members can be compared
-by identity, and the enumeration itself can be iterated over.
-
-.. note:: Case of Enum Members
+.. sidebar:: Important
 
-    Because Enums are used to represent constants we recommend using
-    UPPER_CASE names for enum members, and will be using that style
-    in our examples.
+   This page contains the API reference information. For tutorial
+   information and discussion of more advanced topics, see
 
+   * :ref:`Basic Tutorial <enum-basic-tutorial>`
+   * :ref:`Advanced Tutorial <enum-advanced-tutorial>`
+   * :ref:`Enum Cookbook <enum-cookbook>`
 
-Module Contents
----------------
-
-This module defines four enumeration classes that can be used to define unique
-sets of names and values: :class:`Enum`, :class:`IntEnum`, :class:`Flag`, and
-:class:`IntFlag`.  It also defines one decorator, :func:`unique`, and one
-helper, :class:`auto`.
-
-.. class:: Enum
-
-    Base class for creating enumerated constants.  See section
-    `Functional API`_ for an alternate construction syntax.
-
-.. class:: IntEnum
-
-    Base class for creating enumerated constants that are also
-    subclasses of :class:`int`.
-
-.. class:: StrEnum
-
-    Base class for creating enumerated constants that are also
-    subclasses of :class:`str`.
-
-.. class:: IntFlag
-
-    Base class for creating enumerated constants that can be combined using
-    the bitwise operators without losing their :class:`IntFlag` membership.
-    :class:`IntFlag` members are also subclasses of :class:`int`.
-
-.. class:: Flag
-
-    Base class for creating enumerated constants that can be combined using
-    the bitwise operations without losing their :class:`Flag` membership.
-
-.. function:: unique
-    :noindex:
-
-    Enum class decorator that ensures only one name is bound to any one value.
-
-.. class:: auto
-
-    Instances are replaced with an appropriate value for Enum members.
-    :class:`StrEnum` defaults to the lower-cased version of the member name,
-    while other Enums default to 1 and increase from there.
-
-.. versionadded:: 3.6  ``Flag``, ``IntFlag``, ``auto``
-.. versionadded:: 3.10  ``StrEnum``
-
-Creating an Enum
 ----------------
 
-Enumerations are created using the :keyword:`class` syntax, which makes them
-easy to read and write.  An alternative creation method is described in
-`Functional API`_.  To define an enumeration, subclass :class:`Enum` as
-follows::
-
-    >>> from enum import Enum
-    >>> class Color(Enum):
-    ...     RED = 1
-    ...     GREEN = 2
-    ...     BLUE = 3
-    ...
-
-.. note:: Enum member values
-
-    Member values can be anything: :class:`int`, :class:`str`, etc..  If
-    the exact value is unimportant you may use :class:`auto` instances and an
-    appropriate value will be chosen for you.  Care must be taken if you mix
-    :class:`auto` with other values.
+An enumeration:
 
-.. note:: Nomenclature
-
-  - The class :class:`Color` is an *enumeration* (or *enum*)
-  - The attributes :attr:`Color.RED`, :attr:`Color.GREEN`, etc., are
-    *enumeration members* (or *enum members*) and are functionally constants.
-  - The enum members have *names* and *values* (the name of
-    :attr:`Color.RED` is ``RED``, the value of :attr:`Color.BLUE` is
-    ``3``, etc.)
-
-.. note::
-
-    Even though we use the :keyword:`class` syntax to create Enums, Enums
-    are not normal Python classes.  See `How are Enums different?`_ for
-    more details.
-
-Enumeration members have human readable string representations::
-
-    >>> print(Color.RED)
-    Color.RED
-
-...while their ``repr`` has more information::
-
-    >>> print(repr(Color.RED))
-    <Color.RED: 1>
-
-The *type* of an enumeration member is the enumeration it belongs to::
-
-    >>> type(Color.RED)
-    <enum 'Color'>
-    >>> isinstance(Color.GREEN, Color)
-    True
-
-Enum members also have a property that contains just their item name::
-
-    >>> print(Color.RED.name)
-    RED
-
-Enumerations support iteration, in definition order::
-
-    >>> class Shake(Enum):
-    ...     VANILLA = 7
-    ...     CHOCOLATE = 4
-    ...     COOKIES = 9
-    ...     MINT = 3
-    ...
-    >>> for shake in Shake:
-    ...     print(shake)
-    ...
-    Shake.VANILLA
-    Shake.CHOCOLATE
-    Shake.COOKIES
-    Shake.MINT
-
-Enumeration members are hashable, so they can be used in dictionaries and sets::
-
-    >>> apples = {}
-    >>> apples[Color.RED] = 'red delicious'
-    >>> apples[Color.GREEN] = 'granny smith'
-    >>> apples == {Color.RED: 'red delicious', Color.GREEN: 'granny smith'}
-    True
+* is a set of symbolic names (members) bound to unique values
+* can be iterated over to return its members in definition order
+* uses :meth:`call` syntax to return members by value
+* uses :meth:`index` syntax to return members by name
 
+Enumerations are created either by using the :keyword:`class` syntax, or by
+using function-call syntax::
 
-Programmatic access to enumeration members and their attributes
----------------------------------------------------------------
+   >>> from enum import Enum
 
-Sometimes it's useful to access members in enumerations programmatically (i.e.
-situations where ``Color.RED`` won't do because the exact color is not known
-at program-writing time).  ``Enum`` allows such access::
+   >>> # class syntax
+   >>> class Color(Enum):
+   ...     RED = 1
+   ...     GREEN = 2
+   ...     BLUE = 3
 
-    >>> Color(1)
-    <Color.RED: 1>
-    >>> Color(3)
-    <Color.BLUE: 3>
+   >>> # functional syntax
+   >>> Color = Enum('Color', ['RED', 'GREEN', 'BLUE'])
 
-If you want to access enum members by *name*, use item access::
+Even though we can use the :keyword:`class` syntax to create Enums, Enums
+are not normal Python classes.  See
+:ref:`How are Enums different? <enum-class-differences>` for more details.
 
-    >>> Color['RED']
-    <Color.RED: 1>
-    >>> Color['GREEN']
-    <Color.GREEN: 2>
-
-If you have an enum member and need its :attr:`name` or :attr:`value`::
-
-    >>> member = Color.RED
-    >>> member.name
-    'RED'
-    >>> member.value
-    1
-
-
-Duplicating enum members and values
------------------------------------
-
-Having two enum members with the same name is invalid::
-
-    >>> class Shape(Enum):
-    ...     SQUARE = 2
-    ...     SQUARE = 3
-    ...
-    Traceback (most recent call last):
-    ...
-    TypeError: 'SQUARE' already defined as: 2
-
-However, two enum members are allowed to have the same value.  Given two members
-A and B with the same value (and A defined first), B is an alias to A.  By-value
-lookup of the value of A and B will return A.  By-name lookup of B will also
-return A::
-
-    >>> class Shape(Enum):
-    ...     SQUARE = 2
-    ...     DIAMOND = 1
-    ...     CIRCLE = 3
-    ...     ALIAS_FOR_SQUARE = 2
-    ...
-    >>> Shape.SQUARE
-    <Shape.SQUARE: 2>
-    >>> Shape.ALIAS_FOR_SQUARE
-    <Shape.SQUARE: 2>
-    >>> Shape(2)
-    <Shape.SQUARE: 2>
-
-.. note::
-
-    Attempting to create a member with the same name as an already
-    defined attribute (another member, a method, etc.) or attempting to create
-    an attribute with the same name as a member is not allowed.
-
-
-Ensuring unique enumeration values
-----------------------------------
-
-By default, enumerations allow multiple names as aliases for the same value.
-When this behavior isn't desired, the following decorator can be used to
-ensure each value is used only once in the enumeration:
-
-.. decorator:: unique
-
-A :keyword:`class` decorator specifically for enumerations.  It searches an
-enumeration's :attr:`__members__` gathering any aliases it finds; if any are
-found :exc:`ValueError` is raised with the details::
-
-    >>> from enum import Enum, unique
-    >>> @unique
-    ... class Mistake(Enum):
-    ...     ONE = 1
-    ...     TWO = 2
-    ...     THREE = 3
-    ...     FOUR = 3
-    ...
-    Traceback (most recent call last):
-    ...
-    ValueError: duplicate values found in <enum 'Mistake'>: FOUR -> THREE
-
-
-Using automatic values
-----------------------
-
-If the exact value is unimportant you can use :class:`auto`::
-
-    >>> from enum import Enum, auto
-    >>> class Color(Enum):
-    ...     RED = auto()
-    ...     BLUE = auto()
-    ...     GREEN = auto()
-    ...
-    >>> list(Color)
-    [<Color.RED: 1>, <Color.BLUE: 2>, <Color.GREEN: 3>]
-
-The values are chosen by :func:`_generate_next_value_`, which can be
-overridden::
-
-    >>> class AutoName(Enum):
-    ...     def _generate_next_value_(name, start, count, last_values):
-    ...         return name
-    ...
-    >>> class Ordinal(AutoName):
-    ...     NORTH = auto()
-    ...     SOUTH = auto()
-    ...     EAST = auto()
-    ...     WEST = auto()
-    ...
-    >>> list(Ordinal)
-    [<Ordinal.NORTH: 'NORTH'>, <Ordinal.SOUTH: 'SOUTH'>, <Ordinal.EAST: 'EAST'>, <Ordinal.WEST: 'WEST'>]
-
-.. note::
-
-    The goal of the default :meth:`_generate_next_value_` method is to provide
-    the next :class:`int` in sequence with the last :class:`int` provided, but
-    the way it does this is an implementation detail and may change.
-
-.. note::
-
-    The :meth:`_generate_next_value_` method must be defined before any members.
-
-Iteration
----------
-
-Iterating over the members of an enum does not provide the aliases::
-
-    >>> list(Shape)
-    [<Shape.SQUARE: 2>, <Shape.DIAMOND: 1>, <Shape.CIRCLE: 3>]
-
-The special attribute ``__members__`` is a read-only ordered mapping of names
-to members.  It includes all names defined in the enumeration, including the
-aliases::
-
-    >>> for name, member in Shape.__members__.items():
-    ...     name, member
-    ...
-    ('SQUARE', <Shape.SQUARE: 2>)
-    ('DIAMOND', <Shape.DIAMOND: 1>)
-    ('CIRCLE', <Shape.CIRCLE: 3>)
-    ('ALIAS_FOR_SQUARE', <Shape.SQUARE: 2>)
-
-The ``__members__`` attribute can be used for detailed programmatic access to
-the enumeration members.  For example, finding all the aliases::
-
-    >>> [name for name, member in Shape.__members__.items() if member.name != name]
-    ['ALIAS_FOR_SQUARE']
+.. note:: Nomenclature
 
+   - The class :class:`Color` is an *enumeration* (or *enum*)
+   - The attributes :attr:`Color.RED`, :attr:`Color.GREEN`, etc., are
+     *enumeration members* (or *enum members*) and are functionally constants.
+   - The enum members have *names* and *values* (the name of
+     :attr:`Color.RED` is ``RED``, the value of :attr:`Color.BLUE` is
+     ``3``, etc.)
 
-Comparisons
------------
 
-Enumeration members are compared by identity::
+Module Contents
+---------------
 
-    >>> Color.RED is Color.RED
-    True
-    >>> Color.RED is Color.BLUE
-    False
-    >>> Color.RED is not Color.BLUE
-    True
+   :class:`EnumType`
 
-Ordered comparisons between enumeration values are *not* supported.  Enum
-members are not integers (but see `IntEnum`_ below)::
-
-    >>> Color.RED < Color.BLUE
-    Traceback (most recent call last):
-      File "<stdin>", line 1, in <module>
-    TypeError: '<' not supported between instances of 'Color' and 'Color'
-
-Equality comparisons are defined though::
-
-    >>> Color.BLUE == Color.RED
-    False
-    >>> Color.BLUE != Color.RED
-    True
-    >>> Color.BLUE == Color.BLUE
-    True
+      The ``type`` for Enum and its subclasses.
 
-Comparisons against non-enumeration values will always compare not equal
-(again, :class:`IntEnum` was explicitly designed to behave differently, see
-below)::
+   :class:`Enum`
 
-    >>> Color.BLUE == 2
-    False
+      Base class for creating enumerated constants.
 
+   :class:`IntEnum`
 
-Allowed members and attributes of enumerations
-----------------------------------------------
+      Base class for creating enumerated constants that are also
+      subclasses of :class:`int`.
 
-The examples above use integers for enumeration values.  Using integers is
-short and handy (and provided by default by the `Functional API`_), but not
-strictly enforced.  In the vast majority of use-cases, one doesn't care what
-the actual value of an enumeration is.  But if the value *is* important,
-enumerations can have arbitrary values.
+   :class:`StrEnum`
 
-Enumerations are Python classes, and can have methods and special methods as
-usual.  If we have this enumeration::
+      Base class for creating enumerated constants that are also
+      subclasses of :class:`str`.
 
-    >>> class Mood(Enum):
-    ...     FUNKY = 1
-    ...     HAPPY = 3
-    ...
-    ...     def describe(self):
-    ...         # self is the member here
-    ...         return self.name, self.value
-    ...
-    ...     def __str__(self):
-    ...         return 'my custom str! {0}'.format(self.value)
-    ...
-    ...     @classmethod
-    ...     def favorite_mood(cls):
-    ...         # cls here is the enumeration
-    ...         return cls.HAPPY
-    ...
+   :class:`Flag`
 
-Then::
+      Base class for creating enumerated constants that can be combined using
+      the bitwise operations without losing their :class:`Flag` membership.
 
-    >>> Mood.favorite_mood()
-    <Mood.HAPPY: 3>
-    >>> Mood.HAPPY.describe()
-    ('HAPPY', 3)
-    >>> str(Mood.FUNKY)
-    'my custom str! 1'
-
-The rules for what is allowed are as follows: names that start and end with
-a single underscore are reserved by enum and cannot be used; all other
-attributes defined within an enumeration will become members of this
-enumeration, with the exception of special methods (:meth:`__str__`,
-:meth:`__add__`, etc.), descriptors (methods are also descriptors), and
-variable names listed in :attr:`_ignore_`.
-
-Note:  if your enumeration defines :meth:`__new__` and/or :meth:`__init__` then
-any value(s) given to the enum member will be passed into those methods.
-See `Planet`_ for an example.
-
-
-Restricted Enum subclassing
----------------------------
-
-A new :class:`Enum` class must have one base Enum class, up to one concrete
-data type, and as many :class:`object`-based mixin classes as needed.  The
-order of these base classes is::
-
-    class EnumName([mix-in, ...,] [data-type,] base-enum):
-        pass
-
-Also, subclassing an enumeration is allowed only if the enumeration does not define
-any members.  So this is forbidden::
-
-    >>> class MoreColor(Color):
-    ...     PINK = 17
-    ...
-    Traceback (most recent call last):
-    ...
-    TypeError: MoreColor: cannot extend enumeration 'Color'
-
-But this is allowed::
-
-    >>> class Foo(Enum):
-    ...     def some_behavior(self):
-    ...         pass
-    ...
-    >>> class Bar(Foo):
-    ...     HAPPY = 1
-    ...     SAD = 2
-    ...
-
-Allowing subclassing of enums that define members would lead to a violation of
-some important invariants of types and instances.  On the other hand, it makes
-sense to allow sharing some common behavior between a group of enumerations.
-(See `OrderedEnum`_ for an example.)
-
-
-Pickling
---------
-
-Enumerations can be pickled and unpickled::
-
-    >>> from test.test_enum import Fruit
-    >>> from pickle import dumps, loads
-    >>> Fruit.TOMATO is loads(dumps(Fruit.TOMATO))
-    True
-
-The usual restrictions for pickling apply: picklable enums must be defined in
-the top level of a module, since unpickling requires them to be importable
-from that module.
+   :class:`IntFlag`
 
-.. note::
+      Base class for creating enumerated constants that can be combined using
+      the bitwise operators without losing their :class:`IntFlag` membership.
+      :class:`IntFlag` members are also subclasses of :class:`int`.
 
-    With pickle protocol version 4 it is possible to easily pickle enums
-    nested in other classes.
+   :class:`FlagBoundary`
 
-It is possible to modify how Enum members are pickled/unpickled by defining
-:meth:`__reduce_ex__` in the enumeration class.
+      An enumeration with the values ``STRICT``, ``CONFORM``, ``EJECT``, and
+      ``KEEP`` which allows for more fine-grained control over how invalid values
+      are dealt with in an enumeration.
 
+   :class:`auto`
 
-Functional API
---------------
+      Instances are replaced with an appropriate value for Enum members.
+      :class:`StrEnum` defaults to the lower-cased version of the member name,
+      while other Enums default to 1 and increase from there.
 
-The :class:`Enum` class is callable, providing the following functional API::
+   :func:`global_enum`
 
-    >>> Animal = Enum('Animal', 'ANT BEE CAT DOG')
-    >>> Animal
-    <enum 'Animal'>
-    >>> Animal.ANT
-    <Animal.ANT: 1>
-    >>> Animal.ANT.value
-    1
-    >>> list(Animal)
-    [<Animal.ANT: 1>, <Animal.BEE: 2>, <Animal.CAT: 3>, <Animal.DOG: 4>]
+      :class:`Enum` class decorator to apply the appropriate global `__repr__`,
+      and export its members into the global name space.
 
-The semantics of this API resemble :class:`~collections.namedtuple`. The first
-argument of the call to :class:`Enum` is the name of the enumeration.
+   :func:`property`
 
-The second argument is the *source* of enumeration member names.  It can be a
-whitespace-separated string of names, a sequence of names, a sequence of
-2-tuples with key/value pairs, or a mapping (e.g. dictionary) of names to
-values.  The last two options enable assigning arbitrary values to
-enumerations; the others auto-assign increasing integers starting with 1 (use
-the ``start`` parameter to specify a different starting value).  A
-new class derived from :class:`Enum` is returned.  In other words, the above
-assignment to :class:`Animal` is equivalent to::
+      Allows :class:`Enum` members to have attributes without conflicting with
+      other members' names.
 
-    >>> class Animal(Enum):
-    ...     ANT = 1
-    ...     BEE = 2
-    ...     CAT = 3
-    ...     DOG = 4
-    ...
+   :func:`unique`
 
-The reason for defaulting to ``1`` as the starting number and not ``0`` is
-that ``0`` is ``False`` in a boolean sense, but enum members all evaluate
-to ``True``.
+      Enum class decorator that ensures only one name is bound to any one value.
 
-Pickling enums created with the functional API can be tricky as frame stack
-implementation details are used to try and figure out which module the
-enumeration is being created in (e.g. it will fail if you use a utility
-function in separate module, and also may not work on IronPython or Jython).
-The solution is to specify the module name explicitly as follows::
 
-    >>> Animal = Enum('Animal', 'ANT BEE CAT DOG', module=__name__)
+.. versionadded:: 3.6  ``Flag``, ``IntFlag``, ``auto``
+.. versionadded:: 3.10  ``StrEnum``
 
-.. warning::
 
-    If ``module`` is not supplied, and Enum cannot determine what it is,
-    the new Enum members will not be unpicklable; to keep errors closer to
-    the source, pickling will be disabled.
+Data Types
+----------
 
-The new pickle protocol 4 also, in some circumstances, relies on
-:attr:`~definition.__qualname__` being set to the location where pickle will be able
-to find the class.  For example, if the class was made available in class
-SomeData in the global scope::
 
-    >>> Animal = Enum('Animal', 'ANT BEE CAT DOG', qualname='SomeData.Animal')
+.. class:: EnumType
 
-The complete signature is::
+   *EnumType* is the :term:`metaclass` for *enum* enumerations.  It is possible
+   to subclass *EnumType* -- see :ref:`Subclassing EnumType <enumtype-examples>`
+   for details.
 
-    Enum(value='NewEnumName', names=<...>, *, module='...', qualname='...', type=<mixed-in class>, start=1)
+   .. method:: EnumType.__contains__(cls, member)
 
-:value: What the new Enum class will record as its name.
+      Returns ``True`` if member belongs to the ``cls``::
 
-:names: The Enum members.  This can be a whitespace or comma separated string
-  (values will start at 1 unless otherwise specified)::
+        >>> some_var = Color.RED
+        >>> some_var in Color
+        True
 
-    'RED GREEN BLUE' | 'RED,GREEN,BLUE' | 'RED, GREEN, BLUE'
+   .. method:: EnumType.__dir__(cls)
 
-  or an iterator of names::
+      Returns ``['__class__', '__doc__', '__members__', '__module__']`` and the
+      names of the members in *cls*::
 
-    ['RED', 'GREEN', 'BLUE']
+        >>> dir(Color)
+        ['BLUE', 'GREEN', 'RED', '__class__', '__doc__', '__members__', '__module__']
 
-  or an iterator of (name, value) pairs::
+   .. method:: EnumType.__getattr__(cls, name)
 
-    [('CYAN', 4), ('MAGENTA', 5), ('YELLOW', 6)]
+      Returns the Enum member in *cls* matching *name*, or raises an :exc:`AttributeError`::
 
-  or a mapping::
+        >>> Color.GREEN
+        Color.GREEN
 
-    {'CHARTREUSE': 7, 'SEA_GREEN': 11, 'ROSEMARY': 42}
+   .. method:: EnumType.__getitem__(cls, name)
 
-:module: name of module where new Enum class can be found.
+      Returns the Enum member in *cls* matching *name*, or raises an :exc:`KeyError`::
 
-:qualname: where in module new Enum class can be found.
+        >>> Color['BLUE']
+        Color.BLUE
 
-:type: type to mix in to new Enum class.
+   .. method:: EnumType.__iter__(cls)
 
-:start: number to start counting at if only names are passed in.
+      Returns each member in *cls* in definition order::
 
-.. versionchanged:: 3.5
-   The *start* parameter was added.
+        >>> list(Color)
+        [Color.RED, Color.GREEN, Color.BLUE]
 
+   .. method:: EnumType.__len__(cls)
 
-Derived Enumerations
---------------------
+      Returns the number of member in *cls*::
 
-IntEnum
-^^^^^^^
+        >>> len(Color)
+        3
 
-The first variation of :class:`Enum` that is provided is also a subclass of
-:class:`int`.  Members of an :class:`IntEnum` can be compared to integers;
-by extension, integer enumerations of different types can also be compared
-to each other::
+   .. method:: EnumType.__reversed__(cls)
 
-    >>> from enum import IntEnum
-    >>> class Shape(IntEnum):
-    ...     CIRCLE = 1
-    ...     SQUARE = 2
-    ...
-    >>> class Request(IntEnum):
-    ...     POST = 1
-    ...     GET = 2
-    ...
-    >>> Shape == 1
-    False
-    >>> Shape.CIRCLE == 1
-    True
-    >>> Shape.CIRCLE == Request.POST
-    True
+      Returns each member in *cls* in reverse definition order::
 
-However, they still can't be compared to standard :class:`Enum` enumerations::
+        >>> list(reversed(Color))
+        [Color.BLUE, Color.GREEN, Color.RED]
 
-    >>> class Shape(IntEnum):
-    ...     CIRCLE = 1
-    ...     SQUARE = 2
-    ...
-    >>> class Color(Enum):
-    ...     RED = 1
-    ...     GREEN = 2
-    ...
-    >>> Shape.CIRCLE == Color.RED
-    False
 
-:class:`IntEnum` values behave like integers in other ways you'd expect::
+.. class:: Enum
 
-    >>> int(Shape.CIRCLE)
-    1
-    >>> ['a', 'b', 'c'][Shape.CIRCLE]
-    'b'
-    >>> [i for i in range(Shape.SQUARE)]
-    [0, 1]
+   *Enum* is the base class for all *enum* enumerations.
 
+   .. attribute:: Enum.name
 
-StrEnum
-^^^^^^^
+      The name used to define the ``Enum`` member::
 
-The second variation of :class:`Enum` that is provided is also a subclass of
-:class:`str`.  Members of a :class:`StrEnum` can be compared to strings;
-by extension, string enumerations of different types can also be compared
-to each other.  :class:`StrEnum` exists to help avoid the problem of getting
-an incorrect member::
+        >>> Color.BLUE.name
+        'BLUE'
 
-    >>> from enum import StrEnum
-    >>> class Directions(StrEnum):
-    ...     NORTH = 'north',    # notice the trailing comma
-    ...     SOUTH = 'south'
+   .. attribute:: Enum.value
 
-Before :class:`StrEnum`, ``Directions.NORTH`` would have been the :class:`tuple`
-``('north',)``.
+      The value given to the ``Enum`` member::
 
-.. note::
+         >>> Color.RED.value
+         1
 
-    Unlike other Enum's, ``str(StrEnum.member)`` will return the value of the
-    member instead of the usual ``"EnumClass.member"``.
+      .. note:: Enum member values
 
-.. versionadded:: 3.10
+         Member values can be anything: :class:`int`, :class:`str`, etc..  If
+         the exact value is unimportant you may use :class:`auto` instances and an
+         appropriate value will be chosen for you.  Care must be taken if you mix
+         :class:`auto` with other values.
 
+   .. attribute:: Enum._ignore_
 
-IntFlag
-^^^^^^^
+      ``_ignore_`` is only used during creation and is removed from the
+      enumeration once that is complete.
 
-The next variation of :class:`Enum` provided, :class:`IntFlag`, is also based
-on :class:`int`.  The difference being :class:`IntFlag` members can be combined
-using the bitwise operators (&, \|, ^, ~) and the result is still an
-:class:`IntFlag` member, if possible.  However, as the name implies, :class:`IntFlag`
-members also subclass :class:`int` and can be used wherever an :class:`int` is
-used.
+      ``_ignore_`` is a list of names that will not become members, and whose
+      names will also be removed from the completed enumeration.  See
+      :ref:`TimePeriod <enum-time-period>` for an example.
 
-.. note::
+   .. method:: Enum.__call__(cls, value, names=None, \*, module=None, qualname=None, type=None, start=1, boundary=None)
 
-    Any operation on an :class:`IntFlag` member besides the bit-wise operations will
-    lose the :class:`IntFlag` membership.
+      This method is called in two different ways:
 
-.. note::
+      * to look up an existing member:
 
-    Bit-wise operations that result in invalid :class:`IntFlag` values will lose the
-    :class:`IntFlag` membership.
-
-.. versionadded:: 3.6
-.. versionchanged:: 3.10
-
-Sample :class:`IntFlag` class::
-
-    >>> from enum import IntFlag
-    >>> class Perm(IntFlag):
-    ...     R = 4
-    ...     W = 2
-    ...     X = 1
-    ...
-    >>> Perm.R | Perm.W
-    <Perm.R|W: 6>
-    >>> Perm.R + Perm.W
-    6
-    >>> RW = Perm.R | Perm.W
-    >>> Perm.R in RW
-    True
-
-It is also possible to name the combinations::
-
-    >>> class Perm(IntFlag):
-    ...     R = 4
-    ...     W = 2
-    ...     X = 1
-    ...     RWX = 7
-    >>> Perm.RWX
-    <Perm.RWX: 7>
-    >>> ~Perm.RWX
-    <Perm: 0>
-    >>> Perm(7)
-    <Perm.RWX: 7>
+         :cls:   The enum class being called.
+         :value: The value to lookup.
+
+      * to use the ``cls`` enum to create a new enum:
+
+         :cls:   The enum class being called.
+         :value: The name of the new Enum to create.
+         :names: The names/values of the members for the new Enum.
+         :module:    The name of the module the new Enum is created in.
+         :qualname:  The actual location in the module where this Enum can be found.
+         :type:  A mix-in type for the new Enum.
+         :start: The first integer value for the Enum (used by :class:`auto`)
+         :boundary:  How to handle out-of-range values from bit operations (:class:`Flag` only)
+
+   .. method:: Enum.__dir__(self)
+
+      Returns ``['__class__', '__doc__', '__module__', 'name', 'value']`` and
+      any public methods defined on *self.__class__*::
+
+         >>> from datetime import date
+         >>> class Weekday(Enum):
+         ...     MONDAY = 1
+         ...     TUESDAY = 2
+         ...     WEDNESDAY = 3
+         ...     THURSDAY = 4
+         ...     FRIDAY = 5
+         ...     SATURDAY = 6
+         ...     SUNDAY = 7
+         ...     @classmethod
+         ...     def today(cls):
+         ...         print('today is %s' % cls(date.today.isoweekday).naem)
+         >>> dir(Weekday.SATURDAY)
+         ['__class__', '__doc__', '__module__', 'name', 'today', 'value']
+
+   .. method:: Enum._generate_next_value_(name, start, count, last_values)
+
+         :name: The name of the member being defined (e.g. 'RED').
+         :start: The start value for the Enum; the default is 1.
+         :count: The number of members currently defined, not including this one.
+         :last_values: A list of the previous values.
+
+      A *staticmethod* that is used to determine the next value returned by
+      :class:`auto`::
+
+         >>> from enum import auto
+         >>> class PowersOfThree(Enum):
+         ...     @staticmethod
+         ...     def _generate_next_value_(name, start, count, last_values):
+         ...         return (count + 1) * 3
+         ...     FIRST = auto()
+         ...     SECOND = auto()
+         >>> PowersOfThree.SECOND.value
+         6
+
+   .. method:: Enum._missing_(cls, value)
+
+      A *classmethod* for looking up values not found in *cls*.  By default it
+      does nothing, but can be overridden to implement custom search behavior::
+
+         >>> from enum import StrEnum
+         >>> class Build(StrEnum):
+         ...     DEBUG = auto()
+         ...     OPTIMIZED = auto()
+         ...     @classmethod
+         ...     def _missing_(cls, value):
+         ...         value = value.lower()
+         ...         for member in cls:
+         ...             if member.value == value:
+         ...                 return member
+         ...         return None
+         >>> Build.DEBUG.value
+         'debug'
+         >>> Build('deBUG')
+         Build.DEBUG
+
+   .. method:: Enum.__repr__(self)
+
+      Returns the string used for *repr()* calls.  By default, returns the
+      *Enum* name and the member name, but can be overridden::
+
+         >>> class OldStyle(Enum):
+         ...     RETRO = auto()
+         ...     OLD_SCHOOl = auto()
+         ...     YESTERYEAR = auto()
+         ...     def __repr__(self):
+         ...         cls_name = self.__class__.__name__
+         ...         return f'<{cls_name}.{self.name}: {self.value}>'
+         >>> OldStyle.RETRO
+         <OldStyle.RETRO: 1>
+
+   .. method:: Enum.__str__(self)
+
+      Returns the string used for *str()* calls.  By default, returns the
+      member name, but can be overridden::
+
+         >>> class OldStyle(Enum):
+         ...     RETRO = auto()
+         ...     OLD_SCHOOl = auto()
+         ...     YESTERYEAR = auto()
+         ...     def __str__(self):
+         ...         cls_name = self.__class__.__name__
+         ...         return f'{cls_name}.{self.name}'
+         >>> OldStyle.RETRO
+         OldStyle.RETRO
 
 .. note::
 
-    Named combinations are considered aliases.  Aliases do not show up during
-    iteration, but can be returned from by-value lookups.
-
-.. versionchanged:: 3.10
-
-Another important difference between :class:`IntFlag` and :class:`Enum` is that
-if no flags are set (the value is 0), its boolean evaluation is :data:`False`::
-
-    >>> Perm.R & Perm.X
-    <Perm: 0>
-    >>> bool(Perm.R & Perm.X)
-    False
+   Using :class:`auto` with :class:`Enum` results in integers of increasing value,
+   starting with ``1``.
 
-Because :class:`IntFlag` members are also subclasses of :class:`int` they can
-be combined with them (but may lose :class:`IntFlag` membership::
 
-    >>> Perm.X | 4
-    <Perm.R|X: 5>
+.. class:: IntEnum
 
-    >>> Perm.X | 8
-    9
+   *IntEnum* is the same as *Enum*, but its members are also integers and can be
+   used anywhere that an integer can be used.  If any integer operation is performed
+   with an *IntEnum* member, the resulting value loses its enumeration status.
+
+      >>> from enum import IntEnum
+      >>> class Numbers(IntEnum):
+      ...     ONE = 1
+      ...     TWO = 2
+      ...     THREE = 3
+      >>> Numbers.THREE
+      Numbers.THREE
+      >>> Numbers.ONE + Numbers.TWO
+      3
+      >>> Numbers.THREE + 5
+      8
+      >>> Numbers.THREE == 3
+      True
 
 .. note::
 
-    The negation operator, ``~``, always returns an :class:`IntFlag` member with a
-    positive value::
-
-        >>> (~Perm.X).value == (Perm.R|Perm.W).value == 6
-        True
-
-:class:`IntFlag` members can also be iterated over::
-
-    >>> list(RW)
-    [<Perm.R: 4>, <Perm.W: 2>]
-
-.. versionadded:: 3.10
-
-
-Flag
-^^^^
+   Using :class:`auto` with :class:`IntEnum` results in integers of increasing value,
+   starting with ``1``.
 
-The last variation is :class:`Flag`.  Like :class:`IntFlag`, :class:`Flag`
-members can be combined using the bitwise operators (&, \|, ^, ~).  Unlike
-:class:`IntFlag`, they cannot be combined with, nor compared against, any
-other :class:`Flag` enumeration, nor :class:`int`.  While it is possible to
-specify the values directly it is recommended to use :class:`auto` as the
-value and let :class:`Flag` select an appropriate value.
 
-.. versionadded:: 3.6
-
-Like :class:`IntFlag`, if a combination of :class:`Flag` members results in no
-flags being set, the boolean evaluation is :data:`False`::
-
-    >>> from enum import Flag, auto
-    >>> class Color(Flag):
-    ...     RED = auto()
-    ...     BLUE = auto()
-    ...     GREEN = auto()
-    ...
-    >>> Color.RED & Color.GREEN
-    <Color: 0>
-    >>> bool(Color.RED & Color.GREEN)
-    False
-
-Individual flags should have values that are powers of two (1, 2, 4, 8, ...),
-while combinations of flags won't::
-
-    >>> class Color(Flag):
-    ...     RED = auto()
-    ...     BLUE = auto()
-    ...     GREEN = auto()
-    ...     WHITE = RED | BLUE | GREEN
-    ...
-    >>> Color.WHITE
-    <Color.WHITE: 7>
-
-Giving a name to the "no flags set" condition does not change its boolean
-value::
-
-    >>> class Color(Flag):
-    ...     BLACK = 0
-    ...     RED = auto()
-    ...     BLUE = auto()
-    ...     GREEN = auto()
-    ...
-    >>> Color.BLACK
-    <Color.BLACK: 0>
-    >>> bool(Color.BLACK)
-    False
-
-:class:`Flag` members can also be iterated over::
-
-    >>> purple = Color.RED | Color.BLUE
-    >>> list(purple)
-    [<Color.RED: 1>, <Color.BLUE: 2>]
-
-.. versionadded:: 3.10
-
-.. note::
+.. class:: StrEnum
 
-    For the majority of new code, :class:`Enum` and :class:`Flag` are strongly
-    recommended, since :class:`IntEnum` and :class:`IntFlag` break some
-    semantic promises of an enumeration (by being comparable to integers, and
-    thus by transitivity to other unrelated enumerations).  :class:`IntEnum`
-    and :class:`IntFlag` should be used only in cases where :class:`Enum` and
-    :class:`Flag` will not do; for example, when integer constants are replaced
-    with enumerations, or for interoperability with other systems.
-
-
-Others
-^^^^^^
-
-While :class:`IntEnum` is part of the :mod:`enum` module, it would be very
-simple to implement independently::
-
-    class IntEnum(int, Enum):
-        pass
-
-This demonstrates how similar derived enumerations can be defined; for example
-a :class:`StrEnum` that mixes in :class:`str` instead of :class:`int`.
-
-Some rules:
-
-1. When subclassing :class:`Enum`, mix-in types must appear before
-   :class:`Enum` itself in the sequence of bases, as in the :class:`IntEnum`
-   example above.
-2. While :class:`Enum` can have members of any type, once you mix in an
-   additional type, all the members must have values of that type, e.g.
-   :class:`int` above.  This restriction does not apply to mix-ins which only
-   add methods and don't specify another type.
-3. When another data type is mixed in, the :attr:`value` attribute is *not the
-   same* as the enum member itself, although it is equivalent and will compare
-   equal.
-4. %-style formatting:  `%s` and `%r` call the :class:`Enum` class's
-   :meth:`__str__` and :meth:`__repr__` respectively; other codes (such as
-   `%i` or `%h` for IntEnum) treat the enum member as its mixed-in type.
-5. :ref:`Formatted string literals <f-strings>`, :meth:`str.format`,
-   and :func:`format` will use the mixed-in type's :meth:`__format__`
-   unless :meth:`__str__` or :meth:`__format__` is overridden in the subclass,
-   in which case the overridden methods or :class:`Enum` methods will be used.
-   Use the !s and !r format codes to force usage of the :class:`Enum` class's
-   :meth:`__str__` and :meth:`__repr__` methods.
-
-When to use :meth:`__new__` vs. :meth:`__init__`
-------------------------------------------------
-
-:meth:`__new__` must be used whenever you want to customize the actual value of
-the :class:`Enum` member.  Any other modifications may go in either
-:meth:`__new__` or :meth:`__init__`, with :meth:`__init__` being preferred.
-
-For example, if you want to pass several items to the constructor, but only
-want one of them to be the value::
-
-    >>> class Coordinate(bytes, Enum):
-    ...     """
-    ...     Coordinate with binary codes that can be indexed by the int code.
-    ...     """
-    ...     def __new__(cls, value, label, unit):
-    ...         obj = bytes.__new__(cls, [value])
-    ...         obj._value_ = value
-    ...         obj.label = label
-    ...         obj.unit = unit
-    ...         return obj
-    ...     PX = (0, 'P.X', 'km')
-    ...     PY = (1, 'P.Y', 'km')
-    ...     VX = (2, 'V.X', 'km/s')
-    ...     VY = (3, 'V.Y', 'km/s')
-    ...
-
-    >>> print(Coordinate['PY'])
-    Coordinate.PY
-
-    >>> print(Coordinate(3))
-    Coordinate.VY
-
-Interesting examples
---------------------
-
-While :class:`Enum`, :class:`IntEnum`, :class:`IntFlag`, and :class:`Flag` are
-expected to cover the majority of use-cases, they cannot cover them all.  Here
-are recipes for some different types of enumerations that can be used directly,
-or as examples for creating one's own.
-
-
-Omitting values
-^^^^^^^^^^^^^^^
-
-In many use-cases one doesn't care what the actual value of an enumeration
-is. There are several ways to define this type of simple enumeration:
-
-- use instances of :class:`auto` for the value
-- use instances of :class:`object` as the value
-- use a descriptive string as the value
-- use a tuple as the value and a custom :meth:`__new__` to replace the
-  tuple with an :class:`int` value
-
-Using any of these methods signifies to the user that these values are not
-important, and also enables one to add, remove, or reorder members without
-having to renumber the remaining members.
-
-Whichever method you choose, you should provide a :meth:`repr` that also hides
-the (unimportant) value::
-
-    >>> class NoValue(Enum):
-    ...     def __repr__(self):
-    ...         return '<%s.%s>' % (self.__class__.__name__, self.name)
-    ...
-
-
-Using :class:`auto`
-"""""""""""""""""""
-
-Using :class:`auto` would look like::
-
-    >>> class Color(NoValue):
-    ...     RED = auto()
-    ...     BLUE = auto()
-    ...     GREEN = auto()
-    ...
-    >>> Color.GREEN
-    <Color.GREEN>
-
-
-Using :class:`object`
-"""""""""""""""""""""
-
-Using :class:`object` would look like::
-
-    >>> class Color(NoValue):
-    ...     RED = object()
-    ...     GREEN = object()
-    ...     BLUE = object()
-    ...
-    >>> Color.GREEN
-    <Color.GREEN>
-
-
-Using a descriptive string
-""""""""""""""""""""""""""
-
-Using a string as the value would look like::
-
-    >>> class Color(NoValue):
-    ...     RED = 'stop'
-    ...     GREEN = 'go'
-    ...     BLUE = 'too fast!'
-    ...
-    >>> Color.GREEN
-    <Color.GREEN>
-    >>> Color.GREEN.value
-    'go'
-
-
-Using a custom :meth:`__new__`
-""""""""""""""""""""""""""""""
-
-Using an auto-numbering :meth:`__new__` would look like::
-
-    >>> class AutoNumber(NoValue):
-    ...     def __new__(cls):
-    ...         value = len(cls.__members__) + 1
-    ...         obj = object.__new__(cls)
-    ...         obj._value_ = value
-    ...         return obj
-    ...
-    >>> class Color(AutoNumber):
-    ...     RED = ()
-    ...     GREEN = ()
-    ...     BLUE = ()
-    ...
-    >>> Color.GREEN
-    <Color.GREEN>
-    >>> Color.GREEN.value
-    2
-
-To make a more general purpose ``AutoNumber``, add ``*args`` to the signature::
-
-    >>> class AutoNumber(NoValue):
-    ...     def __new__(cls, *args):      # this is the only change from above
-    ...         value = len(cls.__members__) + 1
-    ...         obj = object.__new__(cls)
-    ...         obj._value_ = value
-    ...         return obj
-    ...
-
-Then when you inherit from ``AutoNumber`` you can write your own ``__init__``
-to handle any extra arguments::
-
-    >>> class Swatch(AutoNumber):
-    ...     def __init__(self, pantone='unknown'):
-    ...         self.pantone = pantone
-    ...     AUBURN = '3497'
-    ...     SEA_GREEN = '1246'
-    ...     BLEACHED_CORAL = () # New color, no Pantone code yet!
-    ...
-    >>> Swatch.SEA_GREEN
-    <Swatch.SEA_GREEN>
-    >>> Swatch.SEA_GREEN.pantone
-    '1246'
-    >>> Swatch.BLEACHED_CORAL.pantone
-    'unknown'
+   *StrEnum* is the same as *Enum*, but its members are also strings and can be used
+   in most of the same places that a string can be used.  The result of any string
+   operation performed on or with a *StrEnum* member is not part of the enumeration.
 
-.. note::
+   .. note:: There are places in the stdlib that check for an exact :class:`str`
+             instead of a :class:`str` subclass (i.e. ``type(unknown) == str``
+             instead of ``isinstance(str, unknown)``), and in those locations you
+             will need to use ``str(StrEnum.member)``.
 
-    The :meth:`__new__` method, if defined, is used during creation of the Enum
-    members; it is then replaced by Enum's :meth:`__new__` which is used after
-    class creation for lookup of existing members.
-
-
-OrderedEnum
-^^^^^^^^^^^
-
-An ordered enumeration that is not based on :class:`IntEnum` and so maintains
-the normal :class:`Enum` invariants (such as not being comparable to other
-enumerations)::
-
-    >>> class OrderedEnum(Enum):
-    ...     def __ge__(self, other):
-    ...         if self.__class__ is other.__class__:
-    ...             return self.value >= other.value
-    ...         return NotImplemented
-    ...     def __gt__(self, other):
-    ...         if self.__class__ is other.__class__:
-    ...             return self.value > other.value
-    ...         return NotImplemented
-    ...     def __le__(self, other):
-    ...         if self.__class__ is other.__class__:
-    ...             return self.value <= other.value
-    ...         return NotImplemented
-    ...     def __lt__(self, other):
-    ...         if self.__class__ is other.__class__:
-    ...             return self.value < other.value
-    ...         return NotImplemented
-    ...
-    >>> class Grade(OrderedEnum):
-    ...     A = 5
-    ...     B = 4
-    ...     C = 3
-    ...     D = 2
-    ...     F = 1
-    ...
-    >>> Grade.C < Grade.A
-    True
-
-
-DuplicateFreeEnum
-^^^^^^^^^^^^^^^^^
-
-Raises an error if a duplicate member name is found instead of creating an
-alias::
-
-    >>> class DuplicateFreeEnum(Enum):
-    ...     def __init__(self, *args):
-    ...         cls = self.__class__
-    ...         if any(self.value == e.value for e in cls):
-    ...             a = self.name
-    ...             e = cls(self.value).name
-    ...             raise ValueError(
-    ...                 "aliases not allowed in DuplicateFreeEnum:  %r --> %r"
-    ...                 % (a, e))
-    ...
-    >>> class Color(DuplicateFreeEnum):
-    ...     RED = 1
-    ...     GREEN = 2
-    ...     BLUE = 3
-    ...     GRENE = 2
-    ...
-    Traceback (most recent call last):
-    ...
-    ValueError: aliases not allowed in DuplicateFreeEnum:  'GRENE' --> 'GREEN'
 
 .. note::
 
-    This is a useful example for subclassing Enum to add or change other
-    behaviors as well as disallowing aliases.  If the only desired change is
-    disallowing aliases, the :func:`unique` decorator can be used instead.
-
-
-Planet
-^^^^^^
-
-If :meth:`__new__` or :meth:`__init__` is defined the value of the enum member
-will be passed to those methods::
-
-    >>> class Planet(Enum):
-    ...     MERCURY = (3.303e+23, 2.4397e6)
-    ...     VENUS   = (4.869e+24, 6.0518e6)
-    ...     EARTH   = (5.976e+24, 6.37814e6)
-    ...     MARS    = (6.421e+23, 3.3972e6)
-    ...     JUPITER = (1.9e+27,   7.1492e7)
-    ...     SATURN  = (5.688e+26, 6.0268e7)
-    ...     URANUS  = (8.686e+25, 2.5559e7)
-    ...     NEPTUNE = (1.024e+26, 2.4746e7)
-    ...     def __init__(self, mass, radius):
-    ...         self.mass = mass       # in kilograms
-    ...         self.radius = radius   # in meters
-    ...     @property
-    ...     def surface_gravity(self):
-    ...         # universal gravitational constant  (m3 kg-1 s-2)
-    ...         G = 6.67300E-11
-    ...         return G * self.mass / (self.radius * self.radius)
-    ...
-    >>> Planet.EARTH.value
-    (5.976e+24, 6378140.0)
-    >>> Planet.EARTH.surface_gravity
-    9.802652743337129
+   Using :class:`auto` with :class:`StrEnum` results in values of the member name,
+   lower-cased.
 
 
-TimePeriod
-^^^^^^^^^^
+.. class:: Flag
 
-An example to show the :attr:`_ignore_` attribute in use::
+   *Flag* members support the bitwise operators ``&`` (*AND*), ``|`` (*OR*),
+   ``^`` (*XOR*), and ``~`` (*INVERT*); the results of those operators are members
+   of the enumeration.
 
-    >>> from datetime import timedelta
-    >>> class Period(timedelta, Enum):
-    ...     "different lengths of time"
-    ...     _ignore_ = 'Period i'
-    ...     Period = vars()
-    ...     for i in range(367):
-    ...         Period['day_%d' % i] = i
-    ...
-    >>> list(Period)[:2]
-    [<Period.day_0: datetime.timedelta(0)>, <Period.day_1: datetime.timedelta(days=1)>]
-    >>> list(Period)[-2:]
-    [<Period.day_365: datetime.timedelta(days=365)>, <Period.day_366: datetime.timedelta(days=366)>]
+   .. method:: __contains__(self, value)
 
+      Returns *True* if value is in self::
 
-How are Enums different?
-------------------------
+         >>> from enum import Flag, auto
+         >>> class Color(Flag):
+         ...     RED = auto()
+         ...     GREEN = auto()
+         ...     BLUE = auto()
+         >>> purple = Color.RED | Color.BLUE
+         >>> white = Color.RED | Color.GREEN | Color.BLUE
+         >>> Color.GREEN in purple
+         False
+         >>> Color.GREEN in white
+         True
+         >>> purple in white
+         True
+         >>> white in purple
+         False
 
-Enums have a custom metaclass that affects many aspects of both derived Enum
-classes and their instances (members).
+   .. method:: __iter__(self):
 
+      Returns all contained members::
 
-Enum Classes
-^^^^^^^^^^^^
+         >>> list(Color.RED)
+         [Color.RED]
+         >>> list(purple)
+         [Color.RED, Color.BLUE]
 
-The :class:`EnumMeta` metaclass is responsible for providing the
-:meth:`__contains__`, :meth:`__dir__`, :meth:`__iter__` and other methods that
-allow one to do things with an :class:`Enum` class that fail on a typical
-class, such as `list(Color)` or `some_enum_var in Color`.  :class:`EnumMeta` is
-responsible for ensuring that various other methods on the final :class:`Enum`
-class are correct (such as :meth:`__new__`, :meth:`__getnewargs__`,
-:meth:`__str__` and :meth:`__repr__`).
+   .. method:: __len__(self):
 
+      Returns number of members in flag::
 
-Enum Members (aka instances)
-^^^^^^^^^^^^^^^^^^^^^^^^^^^^
+         >>> len(Color.GREEN)
+         1
+         >>> len(white)
+         3
 
-The most interesting thing about Enum members is that they are singletons.
-:class:`EnumMeta` creates them all while it is creating the :class:`Enum`
-class itself, and then puts a custom :meth:`__new__` in place to ensure
-that no new ones are ever instantiated by returning only the existing
-member instances.
+   .. method:: __bool__(self):
 
+      Returns *True* if any members in flag, *False* otherwise::
 
-Finer Points
-^^^^^^^^^^^^
+         >>> bool(Color.GREEN)
+         True
+         >>> bool(white)
+         True
+         >>> black = Color(0)
+         >>> bool(black)
+         False
 
-Supported ``__dunder__`` names
-""""""""""""""""""""""""""""""
+   .. method:: __or__(self, other)
 
-:attr:`__members__` is a read-only ordered mapping of ``member_name``:``member``
-items.  It is only available on the class.
+      Returns current flag binary or'ed with other::
 
-:meth:`__new__`, if specified, must create and return the enum members; it is
-also a very good idea to set the member's :attr:`_value_` appropriately.  Once
-all the members are created it is no longer used.
+         >>> Color.RED | Color.GREEN
+         Color.RED|Color.GREEN
 
+   .. method:: __and__(self, other)
 
-Supported ``_sunder_`` names
-""""""""""""""""""""""""""""
+      Returns current flag binary and'ed with other::
 
-- ``_name_`` -- name of the member
-- ``_value_`` -- value of the member; can be set / modified in ``__new__``
-
-- ``_missing_`` -- a lookup function used when a value is not found; may be
-  overridden
-- ``_ignore_`` -- a list of names, either as a :class:`list` or a :class:`str`,
-  that will not be transformed into members, and will be removed from the final
-  class
-- ``_order_`` -- used in Python 2/3 code to ensure member order is consistent
-  (class attribute, removed during class creation)
-- ``_generate_next_value_`` -- used by the `Functional API`_ and by
-  :class:`auto` to get an appropriate value for an enum member; may be
-  overridden
+         >>> purple & white
+         Color.RED|Color.BLUE
+         >>> purple & Color.GREEN
+         0x0
 
-.. note::
+   .. method:: __xor__(self, other)
 
-    For standard :class:`Enum` classes the next value chosen is the last value seen
-    incremented by one.
+      Returns current flag binary xor'ed with other::
 
-    For :class:`Flag`-type classes the next value chosen will be the next highest
-    power-of-two, regardless of the last value seen.
+         >>> purple ^ white
+         Color.GREEN
+         >>> purple ^ Color.GREEN
+         Color.RED|Color.GREEN|Color.BLUE
 
-.. versionadded:: 3.6 ``_missing_``, ``_order_``, ``_generate_next_value_``
-.. versionadded:: 3.7 ``_ignore_``
+   .. method:: __invert__(self):
 
-To help keep Python 2 / Python 3 code in sync an :attr:`_order_` attribute can
-be provided.  It will be checked against the actual order of the enumeration
-and raise an error if the two do not match::
+      Returns all the flags in *type(self)* that are not in self::
 
-    >>> class Color(Enum):
-    ...     _order_ = 'RED GREEN BLUE'
-    ...     RED = 1
-    ...     BLUE = 3
-    ...     GREEN = 2
-    ...
-    Traceback (most recent call last):
-    ...
-    TypeError: member order does not match _order_:
-    ['RED', 'BLUE', 'GREEN']
-    ['RED', 'GREEN', 'BLUE']
+         >>> ~white
+         0x0
+         >>> ~purple
+         Color.GREEN
+         >>> ~Color.RED
+         Color.GREEN|Color.BLUE
 
 .. note::
 
-    In Python 2 code the :attr:`_order_` attribute is necessary as definition
-    order is lost before it can be recorded.
-
-
-_Private__names
-"""""""""""""""
-
-Private names are not converted to Enum members, but remain normal attributes.
-
-.. versionchanged:: 3.10
-
-
-``Enum`` member type
-""""""""""""""""""""
+   Using :class:`auto` with :class:`Flag` results in integers that are powers
+   of two, starting with ``1``.
 
-:class:`Enum` members are instances of their :class:`Enum` class, and are
-normally accessed as ``EnumClass.member``.  In Python versions ``3.5`` to
-``3.9`` you could access members from other members -- this practice was
-discouraged, and in ``3.12`` :class:`Enum` will return to not allowing it,
-while in ``3.10`` and ``3.11`` it will raise a :exc:`DeprecationWarning`::
 
-    >>> class FieldTypes(Enum):
-    ...     name = 0
-    ...     value = 1
-    ...     size = 2
-    ...
-    >>> FieldTypes.value.size       # doctest: +SKIP
-    DeprecationWarning: accessing one member from another is not supported,
-      and will be disabled in 3.12
-    <FieldTypes.size: 2>
-
-.. versionchanged:: 3.5
-.. versionchanged:: 3.10
-
-
-Creating members that are mixed with other data types
-"""""""""""""""""""""""""""""""""""""""""""""""""""""
-
-When subclassing other data types, such as :class:`int` or :class:`str`, with
-an :class:`Enum`, all values after the `=` are passed to that data type's
-constructor.  For example::
+.. class:: IntFlag
 
-    >>> class MyEnum(IntEnum):
-    ...     example = '11', 16      # '11' will be interpreted as a hexadecimal
-    ...                             # number
-    >>> MyEnum.example
-    <MyEnum.example: 17>
+   *IntFlag* is the same as *Flag*, but its members are also integers and can be
+   used anywhere that an integer can be used.
 
+      >>> from enum import IntFlag, auto
+      >>> class Color(IntFlag):
+      ...     RED = auto()
+      ...     GREEN = auto()
+      ...     BLUE = auto()
+      >>> Color.RED & 2
+      0x0
+      >>> Color.RED | 2
+      Color.RED|Color.GREEN
 
-Boolean value of ``Enum`` classes and members
-"""""""""""""""""""""""""""""""""""""""""""""
+   If any integer operation is performed with an *IntFlag* member, the result is
+   not an *IntFlag*::
 
-:class:`Enum` members that are mixed with non-:class:`Enum` types (such as
-:class:`int`, :class:`str`, etc.) are evaluated according to the mixed-in
-type's rules; otherwise, all members evaluate as :data:`True`.  To make your
-own Enum's boolean evaluation depend on the member's value add the following to
-your class::
+        >>> Color.RED + 2
+        3
 
-    def __bool__(self):
-        return bool(self.value)
+   If a *Flag* operation is performed with an *IntFlag* member and:
 
-:class:`Enum` classes always evaluate as :data:`True`.
+      * the result is a valid *IntFlag*: an *IntFlag* is returned
+      * the result is not a valid *IntFlag*: the result depends on the *FlagBoundary* setting
 
+.. note::
 
-``Enum`` classes with methods
-"""""""""""""""""""""""""""""
+   Using :class:`auto` with :class:`IntFlag` results in integers that are powers
+   of two, starting with ``1``.
 
-If you give your :class:`Enum` subclass extra methods, like the `Planet`_
-class above, those methods will show up in a :func:`dir` of the member,
-but not of the class::
+.. class:: FlagBoundary
 
-    >>> dir(Planet)
-    ['EARTH', 'JUPITER', 'MARS', 'MERCURY', 'NEPTUNE', 'SATURN', 'URANUS', 'VENUS', '__class__', '__doc__', '__members__', '__module__']
-    >>> dir(Planet.EARTH)
-    ['__class__', '__doc__', '__module__', 'mass', 'name', 'radius', 'surface_gravity', 'value']
+   *FlagBoundary* controls how out-of-range values are handled in *Flag* and its
+   subclasses.
 
+   .. attribute:: STRICT
 
-Combining members of ``Flag``
-"""""""""""""""""""""""""""""
+      Out-of-range values cause a :exc:`ValueError` to be raised.  This is the
+      default for :class:`Flag`::
 
-Iterating over a combination of Flag members will only return the members that
-are comprised of a single bit::
+         >>> from enum import STRICT
+         >>> class StrictFlag(Flag, boundary=STRICT):
+         ...     RED = auto()
+         ...     GREEN = auto()
+         ...     BLUE = auto()
+         >>> StrictFlag(2**2 + 2**4)
+         Traceback (most recent call last):
+         ...
+         ValueError: StrictFlag: invalid value: 20
+             given 0b0 10100
+           allowed 0b0 00111
 
-    >>> class Color(Flag):
-    ...     RED = auto()
-    ...     GREEN = auto()
-    ...     BLUE = auto()
-    ...     MAGENTA = RED | BLUE
-    ...     YELLOW = RED | GREEN
-    ...     CYAN = GREEN | BLUE
-    ...
-    >>> Color(3)
-    <Color.YELLOW: 3>
-    >>> Color(7)
-    <Color.RED|GREEN|BLUE: 7>
+   .. attribute:: CONFORM
 
-``StrEnum`` and :meth:`str.__str__`
-"""""""""""""""""""""""""""""""""""
+      Out-of-range values have invalid values removed, leaving a valid *Flag*
+      value::
 
-An important difference between :class:`StrEnum` and other Enums is the
-:meth:`__str__` method; because :class:`StrEnum` members are strings, some
-parts of Python will read the string data directly, while others will call
-:meth:`str()`. To make those two operations have the same result,
-:meth:`StrEnum.__str__` will be the same as :meth:`str.__str__` so that
-``str(StrEnum.member) == StrEnum.member`` is true.
+         >>> from enum import CONFORM
+         >>> class ConformFlag(Flag, boundary=CONFORM):
+         ...     RED = auto()
+         ...     GREEN = auto()
+         ...     BLUE = auto()
+         >>> ConformFlag(2**2 + 2**4)
+         ConformFlag.BLUE
 
-``Flag`` and ``IntFlag`` minutia
-""""""""""""""""""""""""""""""""
+   .. attribute:: EJECT
 
-The code sample::
+      Out-of-range values lose their *Flag* membership and revert to :class:`int`.
+      This is the default for :class:`IntFlag`::
 
-    >>> class Color(IntFlag):
-    ...     BLACK = 0
-    ...     RED = 1
-    ...     GREEN = 2
-    ...     BLUE = 4
-    ...     PURPLE = RED | BLUE
-    ...     WHITE = RED | GREEN | BLUE
-    ...
+         >>> from enum import EJECT
+         >>> class EjectFlag(Flag, boundary=EJECT):
+         ...     RED = auto()
+         ...     GREEN = auto()
+         ...     BLUE = auto()
+         >>> EjectFlag(2**2 + 2**4)
+         20
 
-- single-bit flags are canonical
-- multi-bit and zero-bit flags are aliases
-- only canonical flags are returned during iteration::
+   .. attribute:: KEEP
 
-    >>> list(Color.WHITE)
-    [<Color.RED: 1>, <Color.GREEN: 2>, <Color.BLUE: 4>]
+      Out-of-range values are kept, and the *Flag* membership is kept.  This is
+      used for some stdlib flags:
 
-- negating a flag or flag set returns a new flag/flag set with the
-  corresponding positive integer value::
+         >>> from enum import KEEP
+         >>> class KeepFlag(Flag, boundary=KEEP):
+         ...     RED = auto()
+         ...     GREEN = auto()
+         ...     BLUE = auto()
+         >>> KeepFlag(2**2 + 2**4)
+         KeepFlag.BLUE|0x10
 
-    >>> Color.GREEN
-    <Color.GREEN: 2>
 
-    >>> ~Color.GREEN
-    <Color.PURPLE: 5>
+Utilites and Decorators
+-----------------------
 
-- names of pseudo-flags are constructed from their members' names::
+.. class:: auto
 
-    >>> (Color.RED | Color.GREEN).name
-    'RED|GREEN'
+   *auto* can be used in place of a value.  If used, the *Enum* machinery will
+   call an *Enum*'s :meth:`_generate_next_value_` to get an appropriate value.
+   For *Enum* and *IntEnum* that appropriate value will be the last value plus
+   one; for *Flag* and *IntFlag* it will be the first power-of-two greater
+   than the last value; for *StrEnum* it will be the lower-cased version of the
+   member's name.
 
-- multi-bit flags, aka aliases, can be returned from operations::
+   ``_generate_next_value_`` can be overridden to customize the values used by
+   *auto*.
 
-    >>> Color.RED | Color.BLUE
-    <Color.PURPLE: 5>
+.. decorator:: global_enum
 
-    >>> Color(7)  # or Color(-1)
-    <Color.WHITE: 7>
+   A :keyword:`class` decorator specifically for enumerations.  It replaces the
+   :meth:`__repr__` method with one that shows *module_name*.*member_name*.  It
+   also injects the members, and their aliases, into the the global namespace
+   they were defined in.
 
-- membership / containment checking has changed slightly -- zero valued flags
-  are never considered to be contained::
 
-    >>> Color.BLACK in Color.WHITE
-    False
+.. decorator:: property
 
-  otherwise, if all bits of one flag are in the other flag, True is returned::
+   A decorator similar to the built-in *property*, but specifically for
+   enumerations.  It allows member attributes to have the same names as members
+   themselves.
 
-    >>> Color.PURPLE in Color.WHITE
-    True
+   .. note:: the *property* and the member must be defined in separate classes;
+             for example, the *value* and *name* attributes are defined in the
+             *Enum* class, and *Enum* subclasses can define members with the
+             names ``value`` and ``name``.
 
-There is a new boundary mechanism that controls how out-of-range / invalid
-bits are handled: ``STRICT``, ``CONFORM``, ``EJECT``, and ``KEEP``:
+.. decorator:: unique
 
-  * STRICT --> raises an exception when presented with invalid values
-  * CONFORM --> discards any invalid bits
-  * EJECT --> lose Flag status and become a normal int with the given value
-  * KEEP --> keep the extra bits
-           - keeps Flag status and extra bits
-           - extra bits do not show up in iteration
-           - extra bits do show up in repr() and str()
+   A :keyword:`class` decorator specifically for enumerations.  It searches an
+   enumeration's :attr:`__members__`, gathering any aliases it finds; if any are
+   found :exc:`ValueError` is raised with the details::
+
+      >>> from enum import Enum, unique
+      >>> @unique
+      ... class Mistake(Enum):
+      ...     ONE = 1
+      ...     TWO = 2
+      ...     THREE = 3
+      ...     FOUR = 3
+      ...
+      Traceback (most recent call last):
+      ...
+      ValueError: duplicate values found in <enum 'Mistake'>: FOUR -> THREE
 
-The default for Flag is ``STRICT``, the default for ``IntFlag`` is ``DISCARD``,
-and the default for ``_convert_`` is ``KEEP`` (see ``ssl.Options`` for an
-example of when ``KEEP`` is needed).