22.8.2

New error codes:

• Y047: Detect unused TypeAlias declarations.
• Y049: Detect unused TypedDict definitions.
• Y050: Prefer typing_extensions.Never for argument annotations over
  typing.NoReturn.
• Y051: Detect redundant unions between Literal types and builtin supertypes
  (e.g. Literal["foo"] | str, or Literal[5] | int).

Other enhancements:

• Support mypy_extensions.TypedDict.