def load_optimizer_states(self, fname):
        """Loads optimizer (updater) state from a file.

        Parameters
        ----------
        fname : str
            Path to input states file.
        """
        assert self.optimizer_initialized

        if self._update_on_kvstore:
            self._kvstore.load_optimizer_states(fname)
        else:
            self._updater.set_states(open(fname, 'rb').read())