Fix Argument 1 to "__call__" of "TranslationFunction" has incompatible type
There is some cases where the `get_description` method will return None. The TranslationFunction assume the first parameter will be a string, not None. Alternative solutions: - update the condition: vtype is not None and != "Any" (picked solution) - assert returned value is not None whenever necessary - update TranslationFunction signature to take first parameter as Optional[str]. - update all the `get_description` methods to always return a str.