def __call__(self, parser: argparse.ArgumentParser, namespace: argparse.Namespace, values: Union[(str, Sequence[str], None)], option_string: Optional[str]=None) -> None:
    if (not self.appended):
        setattr(namespace, self.dest, [])
        self.appended = True
    getattr(namespace, self.dest).append(values)
def __call__(self, parser: argparse.ArgumentParser, namespace: argparse.Namespace, values: Union[(str, Sequence[str], None)], option_string: Optional[str]=None) -> None:
    if (not self.appended):
        setattr(namespace, self.dest, [])
        self.appended = True
    getattr(namespace, self.dest).append(values)