Add typing_extensions.NamedTuple

Fixes python/typing_extensions#56

Author: AlexWaygood

stdlib/typing_extensions.pyi

@@ -1,6 +1,8 @@
 import abc
+import collections
 import sys
 from _typeshed import IdentityFunction, Self as TypeshedSelf  # see #6932 for why the Self alias cannot have a leading underscore
+from collections.abc import Iterable, 
 from typing import (  # noqa: Y022,Y027,Y039
     TYPE_CHECKING as TYPE_CHECKING,
     Any,
@@ -54,6 +56,7 @@ __all__ = [
     "Counter",
     "Deque",
     "DefaultDict",
+    "NamedTuple",
     "OrderedDict",
     "TypedDict",
     "SupportsIndex",
@@ -196,6 +199,7 @@ else:
 if sys.version_info >= (3, 11):
     from typing import (
         LiteralString as LiteralString,
+        NamedTuple as NamedTuple,  # Ability to create generic NamedTuples is new in 3.11
         Never as Never,
         NotRequired as NotRequired,
         Required as Required,
@@ -237,3 +241,24 @@ else:
         field_specifiers: tuple[type[Any] | Callable[..., Any], ...] = ...,
         **kwargs: object,
     ) -> IdentityFunction: ...
+    
+    class NamedTuple(tuple[Any, ...]):
+        if sys.version_info < (3, 8):
+            _field_types: collections.OrderedDict[str, type]
+        elif sys.version_info < (3, 9):
+            _field_types: dict[str, type]
+        _field_defaults: dict[str, Any]
+        _fields: tuple[str, ...]
+        _source: str
+        @overload
+        def __init__(self, typename: str, fields: Iterable[tuple[str, Any]] = ...) -> None: ...
+        @overload
+        def __init__(self, typename: str, fields: None = ..., **kwargs: Any) -> None: ...
+        @classmethod
+        def _make(cls: type[_T], iterable: Iterable[Any]) -> _T: ...
+        if sys.version_info >= (3, 8):
+            def _asdict(self) -> dict[str, Any]: ...
+        else:
+            def _asdict(self) -> collections.OrderedDict[str, Any]: ...
+
+        def _replace(self: TypeshedSelf, **kwargs: Any) -> TypeshedSelf: ...