def __missing__(self, key):
        if self.default_factory is None:
            raise KeyError(key)
        else:
            ret = self[key] = self.default_factory(name=key)
            return ret
def __init__(self, choices=None, optional=False):
        super().__init__(
            minimum=0, maximum=2 ** 16 - 1, choices=choices, optional=optional
        )