contextlib: add aclosing in py310 (#5317)

* contextlib: add aclosing in py310

* use protocols for closing, aclosing

stdlib/contextlib.pyi

@@ -1,6 +1,7 @@
 import sys
 from types import TracebackType
 from typing import IO, Any, Callable, ContextManager, Iterable, Iterator, Optional, Type, TypeVar, overload
+from typing_extensions import Protocol
 
 if sys.version_info >= (3, 5):
     from typing import AsyncContextManager, AsyncIterator
@@ -34,8 +35,20 @@ if sys.version_info >= (3, 7):
 if sys.version_info < (3,):
     def nested(*mgr: ContextManager[Any]) -> ContextManager[Iterable[Any]]: ...
 
-class closing(ContextManager[_T]):
-    def __init__(self, thing: _T) -> None: ...
+class _SupportsClose(Protocol):
+    def close(self) -> None: ...
+
+_SupportsCloseT = TypeVar("_SupportsCloseT", bound=_SupportsClose)
+
+class closing(ContextManager[_SupportsCloseT]):
+    def __init__(self, thing: _SupportsCloseT) -> None: ...
+
+if sys.version_info >= (3, 10):
+    class _SupportsAclose(Protocol):
+        async def aclose(self) -> None: ...
+    _SupportsAcloseT = TypeVar("_SupportsAcloseT", bound=_SupportsAclose)
+    class aclosing(AsyncContextManager[_SupportsAcloseT]):
+        def __init__(self, thing: _SupportsAcloseT) -> None: ...
 
 if sys.version_info >= (3, 4):
     class suppress(ContextManager[None]):