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 As FunctionType depends on object, this is no longer valid.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.)
- Move Loader and ModuleType into _importlib_modulespec.pyi.
- Add "import X as X" for these to types.pyi and importlib/abc.pyi.
The goal is to ensure mypy -i still works, to fix https://github.com/python/mypy/issues/1797.
* Fix some misspelled method names that were also missing 'self'
* Initial stubs for importlib.machinery
* Use importlib.machinery.ModuleSpec everywhere
