Just ran into an interesting issue with Literal

    >>> l = Literal["foo", "bar", "baz"]
    >>> "foo" in l
    TypeError: typing.Literal['foo', 'bar', 'baz'] is not a generic class
    >>>    
    >>> isinstance("foo", l)
    TypeError: Subscripted generics cannot be used with class and instance checks

So Literal is a Schroedinger's generic.