ipaddress: make _BaseAddress subclass SupportsInt (#1361)

stdlib/3.3/ipaddress.pyi

@@ -1,4 +1,4 @@
-from typing import Any, Iterator, Optional, Tuple, TypeVar, Union
+from typing import Any, Iterator, Optional, SupportsInt, Tuple, TypeVar, Union
 
 _address = Union[bytes, int, str]
 
@@ -24,9 +24,9 @@ class _IPAddressBase(_TotalOrderingMixin):
     @property
     def version(self): ...
 
-class _BaseAddress(_IPAddressBase):
+class _BaseAddress(_IPAddressBase, SupportsInt):
     def __init__(self, address) -> None: ...
-    def __int__(self): ...
+    def __int__(self) -> int: ...
     def __eq__(self, other): ...
     def __lt__(self, other): ...
     def __add__(self, other): ...