def METHOD_NAME(ref_file, trans_file, metric, subword_option=None):
  """Pick a metric and evaluate depending on task."""
  # BLEU scores for translation task
  if metric.lower() == "bleu":
    evaluation_score = _bleu(ref_file, trans_file,
                             subword_option=subword_option)
  # ROUGE scores for summarization tasks
  elif metric.lower() == "rouge":
    evaluation_score = _rouge(ref_file, trans_file,
                              subword_option=subword_option)
  elif metric.lower() == "accuracy":
    evaluation_score = _accuracy(ref_file, trans_file)
  elif metric.lower() == "word_accuracy":
    evaluation_score = _word_accuracy(ref_file, trans_file)
  else:
    raise ValueError("Unknown metric %s" % metric)
  return evaluation_score