Consider __doc__ always Optional. (#641)

python/mypy#2380 showed a discrepancy between object and FunctionType in stdlib2. The first defined __doc__ to be str, the second Optional[str]. As FunctionType depends on object, this is no longer valid.

As suggested by @gvanrossum in python/mypy#2380, all __doc__ should be considered Optional.

(Final verdict was just to remove most __doc__ attributes since it's inherited from object.)

stdlib/3/_importlib_modulespec.pyi

@@ -26,7 +26,6 @@ if sys.version_info >= (3, 4):
 class ModuleType:
     __name__ = ... # type: str
     __file__ = ...  # type: str
-    __doc__ = ... # type: Optional[str]
     if sys.version_info >= (3, 4):
         __loader__ = ... # type: Optional[Loader]
         __package__ = ... # type: Optional[str]

stdlib/3/ast.pyi

@@ -19,12 +19,10 @@ from _ast import (
 )
 
 class NodeVisitor():
-    __doc__ = ...  # type: str
     def visit(self, node: AST) -> Any: ...
     def generic_visit(self, node: AST) -> None: ...
 
 class NodeTransformer(NodeVisitor):
-    __doc__ = ...  # type: str
     def generic_visit(self, node: AST) -> None: ...
 
 def parse(source: Union[str, bytes], filename: Union[str, bytes] = ..., mode: str = ...) -> AST: ...

stdlib/3/builtins.pyi

@@ -28,7 +28,7 @@ class staticmethod: pass   # Special, only valid as a decorator.
 class classmethod: pass  # Special, only valid as a decorator.
 
 class object:
-    __doc__ = ...  # type: str
+    __doc__ = ...  # type: Optional[str]
     __class__ = ...  # type: type
     __dict__ = ...  # type: Dict[str, Any]
 

stdlib/3/types.pyi

@@ -21,7 +21,6 @@ class FunctionType:
     __code__ = ...  # type: CodeType
     __defaults__ = ...  # type: Optional[Tuple[Any, ...]]
     __dict__ = ...  # type: Dict[str, Any]
-    __doc__ = ...  # type: Optional[str]
     __globals__ = ...  # type: Dict[str, Any]
     __name__ = ...  # type: str
     def __call__(self, *args: Any, **kwargs: Any) -> Any: ...