e only Boolean
   objects. The Boolean type is a subtype of the integer type, and
   Boolean values behave like the values 0 and 1, respectively, in
   almost all contexts, the exception being that when converted to a
   string, the strings ""False"" or ""True"" are returned,
   respectively.


"numbers.Real" ("float")
------------------------

These represent machine-level double precision floating-point numbers.
You are at the mercy of the underlying machine architecture (and C or
Java implementation) for the accepted range and handling of overflow.
Python does not support single-precision floating-point numbers; the
savings in processor and memory usage that are usually the reason for
using these are dwarfed by the overhead of using objects in Python, so
there is no reason to complicate the language with two kinds of
floating-point numbers.


"numbers.Complex" ("complex")
-----------------------------

These represent complex numbers as a pair of machine-level double
precision floating-point numbers.  The same caveats apply as for
floating-point numbers. The real and imaginary parts of a complex
number "z" can be retrieved through the read-only attributes "z.real"
and "z.imag".


Sequences
=========

These represent finite ordered sets indexed by non-negative numbers.
The built-in function "len()" returns the number of items of a
sequence. When the length of a sequence is *n*, the index set contains
the numbers 0, 1, …, *n*-1.  Item *i* of sequence *a* is selected by
"a[i]". Some sequences, including built-in sequences, interpret
negative subscripts by adding the sequence length. For example,
"a[-2]" equals "a[n-2]", the second to last item of sequence a with
length "n".

Sequences also support slicing: "a[i:j]" selects all items with index
*k* such that *i* "<=" *k* "<" *j*.  When used as an expression, a
slice is a sequence of the same type. The comment above about negative
indexes also applies to negative slice positions.

Some sequences also support “extended slicing” with a third “step”
parameter: "a[i:j:k]" selects all items of *a* with index *x* where "x
= i + n*k", *n* ">=" "0" and *i* "<=" *x* "<" *j*.

Sequences are distinguished according to their mutability:


Immutable sequences
-------------------

An object of an immutable sequence type cannot change once it is
created.  (If the object contains references to other objects, these
other objects may be mutable and may be changed; however, the
collection of objects directly referenced by an immutable object
cannot change.)

The following types are immutable sequences:

Strings
   A string is a sequence of values that represent Unicode code
   points. All the code points in the range "U+0000 - U+10FFFF" can be
   represented in a string.  Python doesn’t have a char type; instead,
   every code point in the string is represented as a string object
   with length "1".  The built-in function "ord()" converts a code
   point from its string form to an integer in the range "0 - 10FFFF";
   "chr()" converts an integer in the range "0 - 10FFFF" to the
   corresponding length "1" string object. "str.encode()" can be used
   to convert a "str" to "bytes" using the given text encoding, and
   "bytes.decode()" can be used to achieve the opposite.

Tuples
   The items of a tuple are arbitrary Python objects. Tuples of two or
   more items are formed by comma-separated lists of expressions.  A
   tuple of one item (a ‘singleton’) can be formed by affixing a comma
   to an expression (an expression by itself does not create a tuple,
   since parentheses must be usable for grouping of expressions).  An
   empty tuple can be formed by an empty pair of parentheses.

Bytes
   A bytes object is an immutable array.  The items are 8-bit bytes,
   represented by integers in the range 0 <= x < 256.  Bytes literals
   (like "b'abc'") and the built-in "bytes()" constructor can be used
   to create bytes objects.  Also, bytes objects can be decoded to
   strings via the "decode()" method.


Mutable sequences
-----------------

Mutable sequences can be changed after they are created.  The
subscription and slicing notations can be used as the target of
assignment and "del" (delete) statements.

Note:

  The "collections" and "array" module provide additional examples of
  mutable sequence types.

There are currently two intrinsic mutable sequence types:

Lists
   The items of a list are arbitrary Python objects.  Lists are formed
   by placing a comma-separated list of expressions in square
   brackets. (Note that there are no special cases needed to form
   lists of length 0 or 1.)

Byte Arrays
   A bytearray object is a mutable array. They are created by the
   built-in "bytearray()" constructor.  Aside from being mutable (and
   hence unhashable), byte arrays otherwise provide the same interface
   and functionality as immutable "bytes" objects.


Set types
=========

These represent unordered, finite sets of unique, immutable objects.
As such, they cannot be indexed by any subscript. However, they can be
iterated over, and the built-in function "len()" returns the number of
items in a set. Common uses for sets are fast membership testing,
removing duplicates from a sequence, and computing mathematical
operations such as intersection, union, difference, and symmetric
difference.

For set elements, the same immutability rules apply as for dictionary
keys. Note that numeric types obey the normal rules for numeric
comparison: if two numbers compare equal (e.g., "1" and "1.0"), only
one of them can be contained in a set.

There are currently two intrinsic set types:

Sets
   These represent a mutable set. They are created by the built-in
   "set()" constructor and can be modified afterwards by several
   methods, such as "add()".

Frozen sets
   These represent an immutable set.  They are created by the built-in
   "frozenset()" constructor.  As a frozenset is immutable and
   *hashable*, it can be used again as an element of another set, or
   as a dictionary key.


Mappings
========

These represent finite sets of objects indexed by arbitrary index
sets. The subscript notation "a[k]" selects the item indexed by "k"
from the mapping "a"; this can be used in expressions and as the
target of assignments or "del" statements. The built-in function
"len()" returns the number of items in a mapping.

There is currently a single intrinsic mapping type:


Dictionaries
------------

These represent finite sets of objects indexed by nearly arbitrary
values.  The only types of values not acceptable as keys are values
containing lists or dictionaries or other mutable types that are
compared by value rather than by object identity, the reason being
that the efficient implementation of dictionaries requires a key’s
hash value to remain constant. Numeric types used for keys obey the
normal rules for numeric comparison: if two numbers compare equal
(e.g., "1" and "1.0") then they can be used interchangeably to index
the same dictionary entry.

Dictionaries preserve insertion order, meaning that keys will be
produced in the same order they were added sequentially over the
dictionary. Replacing an existing key does not change the order,
however removing a key and re-inserting it will add it to the end
instead of keeping its old place.

Dictionaries are mutable; they can be created by the "{}" notation
(see section Dictionary displays).

The extension modules "dbm.ndbm" and "dbm.gnu" provide additional
examples of mapping types, as does the "collections" module.

Changed in version 3.7: Dictionaries did not preserve insertion order
in versions of Python before 3.6. In CPython 3.6, insertion order was
preserved, but it was considered an implementation detail at that time
rather than a language guarantee.


Callable types
==============

These are the types to which the function call operation (see section
Calls) can be applied:


User-defined functions
----------------------

A user-defined function object is created by a function definition
(see section Function definitions).  It should be called with an
argument list containing the same number of items as the function’s
formal parameter list.


Special read-only attributes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+----------------------------------------------------+----------------------------------------------------+
| Attribute                                          | Meaning                                            |
|====================================================|====================================================|
| function.__globals__                               | A reference to the "dictionary" that holds the     |
|                                                    | function’s global variables – the global namespace |
|                                                    | of the module in which the function was defined.   |
+----------------------------------------------------+----------------------------------------------------+
| function.__closure__                               | "None" or a "tuple" of cells that contain bindings |
|                                                    | for the names specified in the "co_freevars"       |
|                                                    | attribute of the function’s "code object".  A cell |
|                                                    | object has the attribute "cell_contents". This can |
|                                                    | be used to get the value of the cell, as well as   |
|                                                    | set the value.                                     |
+----------------------------------------------------+----------------------------------------------------+


Special writable attributes
~~~~~~~~~~~~~~~~~~~~~~~~~~~

Most of these attributes check the type of the assigned value:

+----------------------------------------------------+----------------------------------------------------+
| Attribute                                          | Meaning                                            |
|====================================================|====================================================|
| function.__doc__                                   | The function’s documentation string, or "None" if  |
|                                                    | unavailable.                                       |
+----------------------------------------------------+----------------------------------------------------+
| function.__name__                                  | The function’s name. See also: "__name__           |
|                                                    | attributes".                                       |
+----------------------------------------------------+----------------------------------------------------+
| function.__qualname__                              | The function’s *qualified name*. See also:         |
|                                                    | "__qualname__ attributes".  Added in version 3.3.  |
+----------------------------------------------------+----------------------------------------------------+
| function.__module__                                | The name of the module the function was defined    |
|                                                    | in, or "None" if unavailable.                      |
+----------------------------------------------------+----------------------------------------------------+
| function.__defaults__                              | A "tuple" containing default *parameter* values    |
|                                                    | for those parameters that have defaults, or "None" |
|                                                    | if no parameters have a default value.             |
+----------------------------------------------------+----------------------------------------------------+
| function.__code__                                  | The code object representing the compiled function |
|                                                    | body.                                              |
+----------------------------------------------------+----------------------------------------------------+
| function.__dict__                                  | The namespace supporting arbitrary function        |
|                                                    | attributes. See also: "__dict__ attributes".       |
+----------------------------------------------------+----------------------------------------------------+
| function.__annotations__                           | A "dictionary" containing annotations of           |
|                                                    | *parameters*. The keys of the dictionary are the   |
|                                                    | parameter names, and "'return'" for the return     |
|                                                    | annotation, if provided. See also: Annotations     |
|                                                    | Best Practices.                                    |
+----------------------------------------------------+----------------------------------------------------+
| function.__kwdefaults__                            | A "dictionary" containing defaults for keyword-    |
|                                                    | only *parameters*.                                 |
+----------------------------------------------------+----------------------------------------------------+
| function.__type_params__                           | A "tuple" containing the type parameters of a      |
|                                                    | generic function.  Added in version 3.12.          |
+----------------------------------------------------+----------------------------------------------------+

Function objects also support getting and setting arbitrary
attributes, which can be used, for example, to attach metadata to
functions.  Regular attribute dot-notation is used to get and set such
attributes.

**CPython implementation detail:** CPython’s current implementation
only supports function attributes on user-defined functions. Function
attributes on built-in functions may be supported in the future.

Additional information about a function’s definition can be retrieved
from its code object (accessible via the "__code__" attribute).


Instance methods
----------------

An instance method object combines a class, a class instance and any
callable object (normally a user-defined function).

Special read-only attributes:

+----------------------------------------------------+----------------------------------------------------+
| method.__self__                                    | Refers to the class instance object to which the   |
|                                                    | method is bound                                    |
+----------------------------------------------------+----------------------------------------------------+
| method.__func__                                    | Refers to the original function object             |
+----------------------------------------------------+----------------------------------------------------+
| method.__doc__                                     | The method’s documentation (same as                |
|                                                    | "method.__func__.__doc__"). A "string" if the      |
|                                                    | original function had a docstring, else "None".    |
+----------------------------------------------------+----------------------------------------------------+
| method.__name__                                    | The name of the method (same as                    |
|                                                    | "method.__func__.__name__")                        |
+----------------------------------------------------+----------------------------------------------------+
| method.__module__                                  | The name of the module the method was defined in,  |
|                                                    | or "None" if unavailable.                          |
+----------------------------------------------------+----------------------------------------------------+

Methods also support accessing (but not setting) the arbitrary
function attributes on the underlying function object.

User-defined method objects may be created when getting an attribute
of a class (perhaps via an instance of that class), if that attribute
is a user-defined function object or a "classmethod" object.

When an instance method object is created by retrieving a user-defined
function object from a class via one of its instances, its "__self__"
attribute is the instance, and the method object is said to be
*bound*.  The new method’s "__func__" attribute is the original
function object.

When an instance method object is created by retrieving a
"classmethod" object from a class or instance, its "__self__"
attribute is the class itself, and its "__func__" attribute is the
function object underlying the class method.

When an instance method object is called, the underlying function
("__func__") is called, inserting the class instance ("__self__") in
front of the argument list.  For instance, when "C" is a class which
contains a definition for a function "f()", and "x" is an instance of
"C", calling "x.f(1)" is equivalent to calling "C.f(x, 1)".

When an instance method object is derived from a "classmethod" object,
the “class instance” stored in "__self__" will actually be the class
itself, so that calling either "x.f(1)" or "C.f(1)" is equivalent to
calling "f(C,1)" where "f" is the underlying function.

It is important to note that user-defined functions which are
attributes of a class instance are not converted to bound methods;
this *only* happens when the function is an attribute of the class.


Generator functions
-------------------

A function or method which uses the "yield" statement (see section The
yield statement) is called a *generator function*.  Such a function,
when called, always returns an *iterator* object which can be used to
execute the body of the function:  calling the iterator’s
"iterator.__next__()" method will cause the function to execute until
it provides a value using the "yield" statement.  When the function
executes a "return" statement or falls off the end, a "StopIteration"
exception is raised and the iterator will have reached the end of the
set of values to be returned.


Coroutine functions
-------------------

A function or method which is defined using "async def" is called a
*coroutine function*.  Such a function, when called, returns a
*coroutine* object.  It may contain "await" expressions, as well as
"async with" and "async for" statements. See also the Coroutine
Objects section.


Asynchronous generator functions
--------------------------------

A function or method which is defined using "async def" and which uses
the "yield" statement is called a *asynchronous generator function*.
Such a function, when called, returns an *asynchronous iterator*
object which can be used in an "async for" statement to execute the
body of the function.

Calling the asynchronous iterator’s "aiterator.__anext__" method will
return an *awaitable* which when awaited will execute until it
provides a value using the "yield" expression.  When the function
executes an empty "return" statement or falls off the end, a
"StopAsyncIteration" exception is raised and the asynchronous iterator
will have reached the end of the set of values to be yielded.


Built-in functions
------------------

A built-in function object is a wrapper around a C function.  Examples
of built-in functions are "len()" and "math.sin()" ("math" is a
standard built-in module). The number and type of the arguments are
determined by the C function. Special read-only attributes:

* "__doc__" is the function’s documentation string, or "None" if
  unavailable. See "function.__doc__".

* "__name__" is the function’s name. See "function.__name__".

* "__self__" is set to "None" (but see the next item).

* "__module__" is the name of the module the function was defined in
  or "None" if unavailable. See "function.__module__".


Built-in methods
----------------

This is really a different disguise of a built-in function, this time
containing an object passed to the C function as an implicit extra
argument.  An example of a built-in method is "alist.append()",
assuming *alist* is a list object. In this case, the special read-only
attribute "__self__" is set to the object denoted by *alist*. (The
attribute has the same semantics as it does with "other instance
methods".)


Classes
-------

Classes are callable.  These objects normally act as factories for new
instances of themselves, but variations are possible for class types
that override "__new__()".  The arguments of the call are passed to
"__new__()" and, in the typical case, to "__init__()" to initialize
the new instance.


Class Instances
---------------

Instances of arbitrary classes can be made callable by defining a
"__call__()" method in their class.


Modules
=======

Modules are a basic organizational unit of Python code, and are
created by the import system as invoked either by the "import"
statement, or by calling functions such as "importlib.import_module()"
and built-in "__import__()".  A module object has a namespace
implemented by a "dictionary" object (this is the dictionary
referenced by the "__globals__" attribute of functions defined in the
module).  Attribute references are translated to lookups in this
dictionary, e.g., "m.x" is equivalent to "m.__dict__["x"]". A module
object does not contain the code object used to initialize the module
(since it isn’t needed once the initialization is done).

Attribute assignment updates the module’s namespace dictionary, e.g.,
"m.x = 1" is equivalent to "m.__dict__["x"] = 1".


Import-related attributes on module objects
-------------------------------------------

Module objects have the following attributes that relate to the import
system. When a module is created using the machinery associated with
the import system, these attributes are filled in based on the
module’s *spec*, before the *loader* executes and loads the module.

To create a module dynamically rather than using the import system,
it’s recommended to use "importlib.util.module_from_spec()", which
will set the various import-controlled attributes to appropriate
values. It’s also possible to use the "types.ModuleType" constructor
to create modules directly, but this technique is more error-prone, as
most attributes must be manually set on the module object after it has
been created when using this approach.

Caution:

  With the exception of "__name__", it is **strongly** recommended
  that you rely on "__spec__" and its attributes instead of any of the
  other individual attributes listed in this subsection. Note that
  updating an attribute on "__spec__" will not update the
  corresponding attribute on the module itself:

     >>> import typing
     >>> typing.__name__, typing.__spec__.name
     ('typing', 'typing')
     >>> typing.__spec__.name = 'spelling'
     >>> typing.__name__, typing.__spec__.name
     ('typing', 'spelling')
     >>> typing.__name__ = 'keyboard_smashing'
     >>> typing.__name__, typing.__spec__.name
     ('keyboard_smashing', 'spelling')

module.__name__

   The name used to uniquely identify the module in the import system.
   For a directly executed module, this will be set to ""__main__"".

   This attribute must be set to the fully qualified name of the
   module. It is expected to match the value of
   "module.__spec__.name".

module.__spec__

   A record of the module’s import-system-related state.

   Set to the "module spec" that was used when importing the module.
   See Module specs for more details.

   Added in version 3.4.

module.__package__

   The *package* a module belongs to.

   If the module is top-level (that is, not a part of any specific
   package) then the attribute should be set to "''" (the empty
   string). Otherwise, it should be set to the name of the module’s
   package (which can be equal to "module.__name__" if the module
   itself is a package). See **PEP 366** for further details.

   This attribute is used instead of "__name__" to calculate explicit
   relative imports for main modules. It defaults to "None" for
   modules created dynamically using the "types.ModuleType"
   constructor; use "importlib.util.module_from_spec()" instead to
   ensure the attribute is set to a "str".

   It is **strongly** recommended that you use
   "module.__spec__.parent" instead of "module.__package__".
   "__package__" is now only used as a fallback if "__spec__.parent"
   is not set, and this fallback path is deprecated.

   Changed in version 3.4: This attribute now defaults to "None" for
   modules created dynamically using the "types.ModuleType"
   constructor. Previously the attribute was optional.

   Changed in version 3.6: The value of "__package__" is expected to
   be the same as "__spec__.parent". "__package__" is now only used as
   a fallback during import resolution if "__spec__.parent" is not
   defined.

   Changed in version 3.10: "ImportWarning" is raised if an import
   resolution falls back to "__package__" instead of
   "__spec__.parent".

   Changed in version 3.12: Raise "DeprecationWarning" instead of
   "ImportWarning" when falling back to "__package__" during import
   resolution.

   Deprecated since version 3.13, will be removed in version 3.15:
   "__package__" will cease to be set or taken into consideration by
   the import system or standard library.

module.__loader__

   The *loader* object that the import machinery used to load the
   module.

   This attribute is mostly useful for introspection, but can be used
   for additional loader-specific functionality, for example getting
   data associated with a loader.

   "__loader__" defaults to "None" for modules created dynamically
   using the "types.ModuleType" constructor; use
   "importlib.util.module_from_spec()" instead to ensure the attribute
   is set to a *loader* object.

   It is **strongly** recommended that you use
   "module.__spec__.loader" instead of "module.__loader__".

   Changed in version 3.4: This attribute now defaults to "None" for
   modules created dynamically using the "types.ModuleType"
   constructor. Previously the attribute was optional.

   Deprecated since version 3.12, will be removed in version 3.16:
   Setting "__loader__" on a module while failing to set
   "__spec__.loader" is deprecated. In Python 3.16, "__loader__" will
   cease to be set or taken into consideration by the import system or
   the standard library.

module.__path__

   A (possibly empty) *sequence* of strings enumerating the locations
   where the package’s submodules will be found. Non-package modules
   should not have a "__path__" attribute. See __path__ attributes on
   modules for more details.

   It is **strongly** recommended that you use
   "module.__spec__.submodule_search_locations" instead of
   "module.__path__".

module.__file__

module.__cached__

   "__file__" and "__cached__" are both optional attributes that may
   or may not be set. Both attributes should be a "str" when they are
   available.

   "__file__" indicates the pathname of the file from which the module
   was loaded (if loaded from a file), or the pathname of the shared
   library file for extension modules loaded dynamically from a shared
   library. It might be missing for certain types of modules, such as
   C modules that are statically linked into the interpreter, and the
   import system may opt to leave it unset if it has no semantic
   meaning (for example, a module loaded from a database).

   If "__file__" is set then the "__cached__" attribute might also be
   set,  which is the path to any compiled version of the code (for
   example, a byte-compiled file). The file does not need to exist to
   set this attribute; the path can simply point to where the compiled
   file *would* exist (see **PEP 3147**).

   Note that "__cached__" may be set even if "__file__" is not set.
   However, that scenario is quite atypical.  Ultimately, the *loader*
   is what makes use of the module spec provided by the *finder* (from
   which "__file__" and "__cached__" are derived).  So if a loader can
   load from a cached module but otherwise does not load from a file,
   that atypical scenario may be appropriate.

   It is **strongly** recommended that you use
   "module.__spec__.cached" instead of "module.__cached__".

   Deprecated since version 3.13, will be removed in version 3.15:
   Setting "__cached__" on a module while failing to set
   "__spec__.cached" is deprecated. In Python 3.15, "__cached__" will
   cease to be set or taken into consideration by the import system or
   standard library.


Other writable attributes on module objects
-------------------------------------------

As well as the import-related attributes listed above, module objects
also have the following writable attributes:

module.__doc__

   The module’s documentation string, or "None" if unavailable. See
   also: "__doc__ attributes".

module.__annotations__

   A dictionary containing *variable annotations* collected during
   module body execution.  For best practices on working with
   "__annotations__", please see Annotations Best Practices.


Module dictionaries
-------------------

Module objects also have the following special read-only attribute:

module.__dict__

   The module’s namespace as a dictionary object. Uniquely among the
   attributes listed here, "__dict__" cannot be accessed as a global
   variable from within a module; it can only be accessed as an
   attribute on module objects.

   **CPython implementation detail:** Because of the way CPython
   clears module dictionaries, the module dictionary will be cleared
   when the module falls out of scope even if the dictionary still has
   live references.  To avoid this, copy the dictionary or keep the
   module around while using its dictionary directly.


Custom classes
==============

Custom class types are typically created by class definitions (see
section Class definitions).  A class has a namespace implemented by a
dictionary object. Class attribute references are translated to
lookups in this dictionary, e.g., "C.x" is translated to
"C.__dict__["x"]" (although there are a number of hooks which allow
for other means of locating attributes). When the attribute name is
not found there, the attribute search continues in the base classes.
This search of the base classes uses the C3 method resolution order
which behaves correctly even in the presence of ‘diamond’ inheritance
structures where there are multiple inheritance paths leading back to
a common ancestor. Additional details on the C3 MRO used by Python can
be found at The Python 2.3 Method Resolution Order.

When a class attribute reference (for class "C", say) would yield a
class method object, it is transformed into an instance method object
whose "__self__" attribute is "C". When it would yield a
"staticmethod" object, it is transformed into the object wrapped by
the static method object. See section Implementing Descriptors for
another way in which attributes retrieved from a class may differ from
those actually contained in its "__dict__".

Class attribute assignments update the class’s dictionary, never the
dictionary of a base class.

A class object can be called (see above) to yield a class instance
(see below).


Special attributes
------------------

+----------------------------------------------------+----------------------------------------------------+
| Attribute                                          | Meaning                                            |
|====================================================|====================================================|
| type.__name__                                      | The class’s name. See also: "__name__ attributes". |
+----------------------------------------------------+----------------------------------------------------+
| type.__qualname__                                  | The class’s *qualified name*. See also:            |
|                                                    | "__qualname__ attributes".                         |
+----------------------------------------------------+----------------------------------------------------+
| type.__module__                                    | The name of the module in which the class was      |
|                                                    | defined.                                           |
+----------------------------------------------------+----------------------------------------------------+
| type.__dict__                                      | A "mapping proxy" providing a read-only view of    |
|                                                    | the class’s namespace. See also: "__dict__         |
|                                                    | attributes".                                       |
+----------------------------------------------------+----------------------------------------------------+
| type.__bases__                                     | A "tuple" containing the class’s bases. In most    |
|                                                    | cases, for a class defined as "class X(A, B, C)",  |
|                                                    | "X.__bases__" will be exactly equal to "(A, B,     |
|                                                    | C)".                                               |
+----------------------------------------------------+----------------------------------------------------+
| type.__doc__                                       | The class’s documentation string, or "None" if     |
|                                                    | undefined. Not inherited by subclasses.            |
+----------------------------------------------------+----------------------------------------------------+
| type.__annotations__                               | A dictionary containing *variable annotations*     |
|                                                    | collected during class body execution. For best    |
|                                                    | practices on working with "__annotations__",       |
|                                                    | please see Annotations Best Practices.  Caution:   |
|                                                    | Accessing the "__annotations__" attribute of a     |
|                                                    | class object directly may yield incorrect results  |
|                                                    | in the presence of metaclasses. In addition, the   |
|                                                    | attribute may not exist for some classes. Use      |
|                                                    | "inspect.get_annotations()" to retrieve class      |
|                                                    | annotations safely.                                |
+----------------------------------------------------+----------------------------------------------------+
| type.__type_params__                               | A "tuple" containing the type parameters of a      |
|                                                    | generic class.  Added in version 3.12.             |
+----------------------------------------------------+----------------------------------------------------+
| type.__static_attributes__                         | A "tuple" containing names of attributes of this   |
|                                                    | class which are assigned through "self.X" from any |
|                                                    | function in its body.  Added in version 3.13.      |
+----------------------------------------------------+----------------------------------------------------+
| type.__firstlineno__                               | The line number of the first line of the class     |
|                                                    | definition, including decorators. Setting the      |
|                                                    | "__module__" attribute removes the                 |
|                                                    | "__firstlineno__" item from the type’s dictionary. |
|                                                    | Added in version 3.13.                             |
+----------------------------------------------------+----------------------------------------------------+
| type.__mro__                                       | The "tuple" of classes that are considered when    |
|                                                    | looking for base classes during method resolution. |
+----------------------------------------------------+----------------------------------------------------+


Special methods
---------------

In addition to the special attributes described above, all Python
classes also have the following two methods available:

type.mro()

   This method can be overridden by a metaclass to customize the
   method resolution order for its instances.  It is called at class
   instantiation, and its result is stored in "__mro__".

type.__subclasses__()

   Each class keeps a list of weak references to its immediate
   subclasses. This method returns a list of all those references
   still alive. The list is in definition order. Example:

      >>> class A: pass
      >>> class B(A): pass
      >>> A.__subclasses__()
      [<class 'B'>]


Class instances
===============

A class instance is created by calling a class object (see above).  A
class instance has a namespace implemented as a dictionary which is
the first place in which attribute references are searched.  When an
attribute is not found there, and the instance’s class has an
attribute by that name, the search continues with the class
attributes.  If a class attribute is found that is a user-defined
function object, it is transformed into an instance method object
whose "__self__" attribute is the instance.  Static method and class
method objects are also transformed; see above under “Classes”.  See
section Implementing Descriptors for another way in which attributes
of a class retrieved via its instances may differ from the objects
actually stored in the class’s "__dict__".  If no class attribute is
found, and the object’s class has a "__getattr__()" method, that is
called to satisfy the lookup.

Attribute assignments and deletions update the instance’s dictionary,
never a class’s dictionary.  If the class has a "__setattr__()" or
"__delattr__()" method, this is called instead of updating the
instance dictionary directly.

Class instances can pretend to be numbers, sequences, or mappings if
they have methods with certain special names.  See section Special
method names.


Special attributes
------------------

object.__class__

   The class to which a class instance belongs.

object.__dict__

   A dictionary or other mapping object used to store an object’s
   (writable) attributes. Not all instances have a "__dict__"
   attribute; see the section on __slots__ for more details.


I/O objects (also known as file objects)
========================================

A *file object* represents an open file.  Various shortcuts are
available to create file objects: the "open()" built-in function, and
also "os.popen()", "os.fdopen()", and the "makefile()" method of
socket objects (and perhaps by other functions or methods provided by
extension modules).

The objects "sys.stdin", "sys.stdout" and "sys.stderr" are initialized
to file objects corresponding to the interpreter’s standard input,
output and error streams; they are all open in text mode and therefore
follow the interface defined by the "io.TextIOBase" abstract class.


Internal types
==============

A few types used internally by the interpreter are exposed to the
user. Their definitions may change with future versions of the
interpreter, but they are mentioned here for completeness.


Code objects
------------

Code objects represent *byte-compiled* executable Python code, or
*bytecode*. The difference between a code object and a function object
is that the function object contains an explicit reference to the
function’s globals (the module in which it was defined), while a code
object contains no context; also the default argument values are
stored in the function object, not in the code object (because they
represent values calculated at run-time).  Unlike function objects,
code objects are immutable and contain no references (directly or
indirectly) to mutable objects.


Special read-only attributes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_name                                 | The function name                                  |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_qualname                             | The fully qualified function name  Added in        |
|                                                    | version 3.11.                                      |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_argcount                             | The total number of positional *parameters*        |
|                                                    | (including positional-only parameters and          |
|                                                    | parameters with default values) that the function  |
|                                                    | has                                                |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_posonlyargcount                      | The number of positional-only *parameters*         |
|                                                    | (including arguments with default values) that the |
|                                                    | function has                                       |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_kwonlyargcount                       | The number of keyword-only *parameters* (including |
|                                                    | arguments with default values) that the function   |
|                                                    | has                                                |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_nlocals                              | The number of local variables used by the function |
|                                                    | (including parameters)                             |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_varnames                             | A "tuple" containing the names of the local        |
|                                                    | variables in the function (starting with the       |
|                                                    | parameter names)                                   |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_cellvars                             | A "tuple" containing the names of local variables  |
|                                                    | that are referenced from at least one *nested      |
|                                                    | scope* inside the function                         |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_freevars                             | A "tuple" containing the names of *free (closure)  |
|                                                    | variables* that a *nested scope* references in an  |
|                                                    | outer scope. See also "function.__closure__".      |
|                                                    | Note: references to global and builtin names are   |
|                                                    | *not* included.                                    |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_code                                 | A string representing the sequence of *bytecode*   |
|                                                    | instructions in the function                       |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_consts                               | A "tuple" containing the literals used by the      |
|                                                    | *bytecode* in the function                         |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_names                                | A "tuple" containing the names used by the         |
|                                                    | *bytecode* in the function                         |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_filename                             | The name of the file from which the code was       |
|                                                    | compiled                                           |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_firstlineno                          | The line number of the first line of the function  |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_lnotab                               | A string encoding the mapping from *bytecode*      |
|                                                    | offsets to line numbers. For details, see the      |
|                                                    | source code of the interpreter.  Deprecated since  |
|                                                    | version 3.12: This attribute of code objects is    |
|                                                    | deprecated, and may be removed in Python 3.15.     |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_stacksize                            | The required stack size of the code object         |
+----------------------------------------------------+----------------------------------------------------+
| codeobject.co_flags                                | An "integer" encoding a number of flags for the    |
|                                                    | interpreter.                                       |
+----------------------------------------------------+----------------------------------------------------+

The following flag bits are defined for "co_flags": bit "0x04" is set
if the function uses the "*arguments" syntax to accept an arbitrary
number of positional arguments; bit "0x08" is set if the function uses
the "**keywords" syntax to accept arbitrary keyword arguments; bit
"0x20" is set if the function is a generator. See Code Objects Bit
Flags for details on the semantics of each flags that might be
present.

Future feature declarations (for example, "from __future__ import
division") also use bits in "co_flags" to indicate whether a code
object was compiled with a particular feature enabled. See
"compiler_flag".

Other bits in "co_flags" are reserved for internal use.

If a code object represents a function, the first item in "co_consts"
is the documentation string of the function, or "None" if undefined.


Methods on code objects
~~~~~~~~~~~~~~~~~~~~~~~

codeobject.co_positions()

   Returns an iterable over the source code positions of each
   *bytecode* instruction in the code object.

   The iterator returns "tuple"s containing the "(start_line,
   end_line, start_column, end_column)". The *i-th* tuple corresponds
   to the position of the source code that compiled to the *i-th* code
   unit. Column information is 0-indexed utf-8 byte offsets on the
   given source line.

   This positional information can be missing. A non-exhaustive lists
   of cases where this may happen:

   * Running the interpreter with "-X" "no_debug_ranges".

   * Loading a pyc file compiled while using "-X" "no_debug_ranges".

   * Position tuples corresponding to artificial instructions.

   * Line and column numbers that can’t be represented due to
     implementation specific limitations.

   When this occurs, some or all of the tuple elements can be "None".

   Added in version 3.11.

   Note:

     This feature requires storing column positions in code objects
     which may result in a small increase of disk usage of compiled
     Python files or interpreter memory usage. To avoid storing the
     extra information and/or deactivate printing the extra traceback
     information, the "-X" "no_debug_ranges" command line flag or the
     "PYTHONNODEBUGRANGES" environment variable can be used.

codeobject.co_lines()

   Returns an iterator that yields information about successive ranges
   of *bytecode*s. Each item yielded is a "(start, end, lineno)"
   "tuple":

   * "start" (an "int") represents the offset (inclusive) of the start
     of the *bytecode* range

   * "end" (an "int") represents the offset (exclusive) of the end of
     the *bytecode* range

   * "lineno" is an "int" representing the line number of the
     *bytecode* range, or "None" if the bytecodes in the given range
     have no line number

   The items yielded will have the following properties:

   * The first range yielded will have a "start" of 0.

   * The "(start, end)" ranges will be non-decreasing and consecutive.
     That is, for any pair of "tuple"s, the "start" of the second will
     be equal to the "end" of the first.

   * No range will be backwards: "end >= start" for all triples.

   * The last "tuple" yielded will have "end" equal to the size of the
     *bytecode*.

   Zero-width ranges, where "start == end", are allowed. Zero-width
   ranges are used for lines that are present in the source code, but
   have been eliminated by the *bytecode* compiler.

   Added in version 3.10.

   See also:

     **PEP 626** - Precise line numbers for debugging and other tools.
        The PEP that introduced the "co_lines()" method.

codeobject.replace(**kwargs)

   Return a copy of the code object with new values for the specified
   fields.

   Code objects are also supported by the generic function
   "copy.replace()".

   Added in version 3.8.


Frame objects
-------------

Frame objects represent execution frames.  They may occur in traceback
objects, and are also passed to registered trace functions.


Special read-only attributes
~~~~~~~~~~~~~~~~~~~~~~~~~~~~

+----------------------------------------------------+----------------------------------------------------+
| frame.f_back                                       | Points to the previous stack frame (towards the    |
|                                                    | caller), or "None" if this is the bottom stack     |
|                                                    | frame                                              |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_code                                       | The code object being executed in this frame.      |
|                                                    | Accessing this attribute raises an auditing event  |
|                                                    | "object.__getattr__" with arguments "obj" and      |
|                                                    | ""f_code"".                                        |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_locals                                     | The mapping used by the frame to look up local     |
|                                                    | variables. If the frame refers to an *optimized    |
|                                                    | scope*, this may return a write-through proxy      |
|                                                    | object.  Changed in version 3.13: Return a proxy   |
|                                                    | for optimized scopes.                              |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_globals                                    | The dictionary used by the frame to look up global |
|                                                    | variables                                          |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_builtins                                   | The dictionary used by the frame to look up built- |
|                                                    | in (intrinsic) names                               |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_lasti                                      | The “precise instruction” of the frame object      |
|                                                    | (this is an index into the *bytecode* string of    |
|                                                    | the code object)                                   |
+----------------------------------------------------+----------------------------------------------------+


Special writable attributes
~~~~~~~~~~~~~~~~~~~~~~~~~~~

+----------------------------------------------------+----------------------------------------------------+
| frame.f_trace                                      | If not "None", this is a function called for       |
|                                                    | various events during code execution (this is used |
|                                                    | by debuggers). Normally an event is triggered for  |
|                                                    | each new source line (see "f_trace_lines").        |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_trace_lines                                | Set this attribute to "False" to disable           |
|                                                    | triggering a tracing event for each source line.   |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_trace_opcodes                              | Set this attribute to "True" to allow per-opcode   |
|                                                    | events to be requested. Note that this may lead to |
|                                                    | undefined interpreter behaviour if exceptions      |
|                                                    | raised by the trace function escape to the         |
|                                                    | function being traced.                             |
+----------------------------------------------------+----------------------------------------------------+
| frame.f_lineno                                     | The current line number of the frame – writing to  |
|                                                    | this from within a trace function jumps to the     |
|                                                    | given line (only for the bottom-most frame).  A    |
|                                                    | debugger can implement a Jump command (aka Set     |
|                                                    | Next Statement) by writing to this attribute.      |
+----------------------------------------------------+----------------------------------------------------+


Frame object methods
~~~~~~~~~~~~~~~~~~~~

Frame objects support one method:

frame.clear()

   This method clears all references to local variables held by the
   frame.  Also, if the frame belonged to a *generator*, the generator
   is finalized.  This helps break reference cycles involving frame
   objects (for example when catching an exception and storing its
   traceback for later use).

   "RuntimeError" is raised if the frame is currently executing or
   suspended.

   Added in version 3.4.

   Changed in version 3.13: Attempting to clear a suspended frame
   raises "RuntimeError" (as has always been the case for executing
   frames).


Traceback objects
-----------------

Traceback objects represent the stack trace of an exception. A
traceback object is implicitly created when an exception occurs, and
may also be explicitly created by calling "types.TracebackType".

Changed in version 3.7: Traceback objects can now be explicitly
instantiated from Python code.

For implicitly created tracebacks, when the search for an exception
handler unwinds the execution stack, at each unwound level a traceback
object is inserted in front of the current traceback.  When an
exception handler is entered, the stack trace is made available to the
program. (See section The try statement.) It is accessible as the
third item of the tuple returned by "sys.exc_info()", and as the
"__traceback__" attribute of the caught exception.

When the program contains no suitable handler, the stack trace is
written (nicely formatted) to the standard error stream; if the
interpreter is interactive, it is also made available to the user as
"sys.last_traceback".

For explicitly created tracebacks, it is up to the creator of the
traceback to determine how the "tb_next" attributes should be linked
to form a full stack trace.

Special read-only attributes:

+----------------------------------------------------+----------------------------------------------------+
| traceback.tb_frame                                 | Points to the execution frame of the current       |
|                                                    | level.  Accessing this attribute raises an         |
|                                                    | auditing event "object.__getattr__" with arguments |
|                                                    | "obj" and ""tb_frame"".                            |
+----------------------------------------------------+----------------------------------------------------+
| traceback.tb_lineno                                | Gives the line number where the exception occurred |
+----------------------------------------------------+----------------------------------------------------+
| traceback.tb_lasti                                 | Indicates the “precise instruction”.               |
+----------------------------------------------------+----------------------------------------------------+

The line number and last instruction in the traceback may differ from
the line number of its frame object if the exception occurred in a
"try" statement with no matching except clause or with a "finally"
clause.

traceback.tb_next

   The special writable attribute "tb_next" is the next level in the
   stack trace (towards the frame where the exception occurred), or
   "None" if there is no next level.

   Changed in version 3.7: This attribute is now writable


Slice objects
-------------

Slice objects are used to represent slices for "__getitem__()"
methods.  They are also created by the built-in "slice()" function.

Special read-only attributes: "start" is the lower bound; "stop" is
the upper bound; "step" is the step value; each is "None" if omitted.
These attributes can have any type.

Slice objects support one method:

slice.indices(self, length)

   This method takes a single integer argument *length* and computes
   information about the slice that the slice object would describe if
   applied to a sequence of *length* items.  It returns a tuple of
   three integers; respectively these are the *start* and *stop*
   indices and the *step* or stride length of the slice. Missing or
   out-of-bounds indices are handled in a manner consistent with
   regular slices.


Static method objects
---------------------

Static method objects provide a way of defeating the transformation of
function objects to method objects described above. A static method
object is a wrapper around any other object, usually a user-defined
method object. When a static method object is retrieved from a class
or a class instance, the object actually returned is the wrapped
object, which is not subject to any further transformation. Static
method objects are also callable. Static method objects are created by
the built-in "staticmethod()" constructor.


Class method objects
--------------------

A class method object, like a static method object, is a wrapper
around another object that alters the way in which that object is
retrieved from classes and class instances. The behaviour of class
method objects upon such retrieval is described above, under “instance
methods”. Class method objects are created by the built-in
"classmethod()" constructor.
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