Make partial a generic type (the parameter being the return type).

Author: Guido van Rossum

stdlib/2.7/functools.pyi

@@ -3,7 +3,7 @@
 # NOTE: This dynamically typed stub was automatically generated by stubgen.
 
 from abc import ABCMeta, abstractmethod
-from typing import Any, Callable, Dict, Iterator, Optional, Sequence, Tuple, TypeVar
+from typing import Any, Callable, Generic, Dict, Iterator, Optional, Sequence, Tuple, TypeVar
 from collections import namedtuple
 
 _AnyCallable = Callable[..., Any]
@@ -21,9 +21,9 @@ def wraps(wrapped: _AnyCallable, assigned: Sequence[str] = ..., updated: Sequenc
 def total_ordering(cls: type) -> type: ...
 def cmp_to_key(mycmp: Callable[[_T, _T], bool]) -> Callable[[_T], Any]: ...
 
-class partial(object):
-    func = ...  # Callable[..., Any]
+class partial(Generic[_T]):
+    func = ...  # Callable[..., _T]
     args = ...  # type: Tuple[Any, ...]
     keywords = ...  # type: Dict[str, Any]
-    def __init__(self, func: Callable[..., Any], *args: Any, **kwargs: Any) -> None: ...
-    def __call__(self, *args: Any, **kwargs: Any) -> Any: ...
+    def __init__(self, func: Callable[..., _T], *args: Any, **kwargs: Any) -> None: ...
+    def __call__(self, *args: Any, **kwargs: Any) -> _T: ...