docs: def rouge_l_fscore(predictions, labels):
    """ROUGE scores computation between labels and predictions.
  
    This is an approximate ROUGE scoring method since we do not glue word pieces
    or decode the ids and tokenize the output.
  
    Args:
      predictions: tensor, model predictions
      labels: tensor, gold output.
  
    Returns:
      rouge_l_fscore: approx rouge-l f1 score.
    """
    outputs = tf.to_int32(tf.argmax(predictions, axis=-1))
    rouge_l_f_score = tf.py_func(rouge_l_sentence_level, (outputs, labels),
                                 tf.float32)
    return rouge_l_f_score, tf.constant(1.0)