@final
def _duplicated(self, keep: Literal[('first', 'last', False)]='first') -> npt.NDArray[np.bool_]:
    return duplicated(self._values, keep=keep)
@final
def _duplicated(self, keep: Literal[('first', 'last', False)]='first') -> npt.NDArray[np.bool_]:
    return duplicated(self._values, keep=keep)