Type alias definition for MISSING results in type violations

[erictraut]

When using pyright to type check the bidict sources, a bunch of type violations are detected. The majority of them are because of the following type alias definition in the _typing.py file:

MISSING: t.Final[MissingT] = MissingT.MISSING

This type alias declares that the type of MISSING is MissingT. The code assumes that its type is Literal[MissingT.MISSING]. You can fix this by changing the above to one of the following:

MISSING: t.Final[t.Literal[MissingT.MISSING]] = MissingT.MISSING

or simply...

MISSING: t.Final = MissingT.MISSING

[jab]

Thanks, @erictraut!