* Annotate three previously missing `MappingProxyType` methods
* `__hash__`
* `__reversed__`
* `__class_getitem__`
* Improve 5 `MappingProxyType` methods
The assumption here is that the underlying mapping is a `dict`,
just is done for `MappingProxyType.copy`
* Make the value type of `types.MappingProxyType` covariant
Add operators or and ror for types.Union and ror to the type class.
Also, add modified isinstance and issubclass signatures to support old-style and new-style unions inside.
This is enough to get stubtest working (note that it's a little annoying
to install mypy currently since typed-ast seems to have broken again on
Python 3.10)
Co-authored-by: hauntsaninja <>
