code: def muc(clusters, mention_to_gold):
          
          true_p, all_p = 0, 0
          for cluster in clusters:
              all_p += len(cluster) - 1
              true_p += len(cluster)
              linked = set()
              for mention in cluster:
                  if mention in mention_to_gold:
                      linked.add(mention_to_gold[mention])
                  else:
                      true_p -= 1
              true_p -= len(linked)
          return true_p, all_p
docs: Counts the mentions in each predicted cluster which need to be re-allocated in
          order for each predicted cluster to be contained by the respective gold cluster.
          <http://aclweb.org/anthology/M/M95/M95-1005.pdf>