Allow reversed to take any object implementing __len__ and __getitem__ (#5820)

`reversed` is currently annotated as accepting either a `Sequence` or objects implementing the `__reversed__` protocol.
This however is too strict as, per its [docs](https://docs.python.org/3/library/functions.html#reversed), it can take any object that implements `__len__` and `__getitem__`.

stdlib/_typeshed/__init__.pyi

@@ -37,6 +37,10 @@ class SupportsDivMod(Protocol[_T_contra, _T_co]):
 class SupportsRDivMod(Protocol[_T_contra, _T_co]):
     def __rdivmod__(self, __other: _T_contra) -> _T_co: ...
 
+class SupportsLenAndGetItem(Protocol[_T_co]):
+    def __len__(self) -> int: ...
+    def __getitem__(self, __k: int) -> _T_co: ...
+
 # Mapping-like protocols
 
 # stable

stdlib/builtins.pyi

@@ -11,6 +11,7 @@ from _typeshed import (
     StrOrBytesPath,
     SupportsDivMod,
     SupportsKeysAndGetItem,
+    SupportsLenAndGetItem,
     SupportsLessThan,
     SupportsLessThanT,
     SupportsRDivMod,
@@ -1286,10 +1287,10 @@ else:
 def quit(code: object = ...) -> NoReturn: ...
 
 class reversed(Iterator[_T], Generic[_T]):
-    @overload
-    def __init__(self, __sequence: Sequence[_T]) -> None: ...
     @overload
     def __init__(self, __sequence: Reversible[_T]) -> None: ...
+    @overload
+    def __init__(self, __sequence: SupportsLenAndGetItem[_T]) -> None: ...
     def __iter__(self) -> Iterator[_T]: ...
     def __next__(self) -> _T: ...
 

stubs/annoy/annoy/__init__.pyi

@@ -1,8 +1,8 @@
-from typing import Sized, overload
-from typing_extensions import Literal, Protocol
+from _typeshed import SupportsLenAndGetItem
+from typing import overload
+from typing_extensions import Literal
 
-class _Vector(Protocol, Sized):
-    def __getitem__(self, i: int) -> float: ...
+_Vector = SupportsLenAndGetItem[float]
 
 class AnnoyIndex:
     f: int