def METHOD_NAME() -> None:
    """Test ParsedSignature."""
    def fn(foo: int, bar: Optional[List[int]] = None) -> None:
        ...
    parsed_sig = ParsedSignature.from_fn(fn, get_fn_type_hints(fn))
    assert parsed_sig.return_type.annotation is NoneType
    assert parsed_sig.parameters["foo"].annotation is int
    assert parsed_sig.parameters["bar"].args == (List[int], NoneType)
    assert parsed_sig.parameters["bar"].annotation == Union[List[int], NoneType]
    assert parsed_sig.parameters["bar"].default is Empty
    assert parsed_sig.original_signature == inspect.signature(fn)