def __str__(self):
        return "\n".join([str(x) for x in self])
def update_state(self, y_true, y_pred, sample_weight=None):
    sample_weight = _apply_mask(y_true, sample_weight, self._masked_tokens,
                                self._dtype)
    sample_weight = tf.reshape(sample_weight, [-1])
    super().update_state(sample_weight)