def METHOD_NAME(self):
    """
    Return the callable that should be used to reconstruct ``self`` upon
    unpickling. If None, default to whatever Python's pickle uses.
    """
    # NOTE: Backward compatibility
    try:
        return self._pickle_reconstruct
    except AttributeError:
        pass
    try:
        return self._rcls
    except AttributeError:
        return None