def __setattr__(self, key: str, value: Any) -> None:
    if (key == 'children'):
        assert False
    else:
        return super().__setattr__(key, value)
def __setattr__(self, key: str, value: Any) -> None:
    if (key == 'children'):
        assert False
    else:
        return super().__setattr__(key, value)