code: def normalized_mutual_info_score(self, reference_clusters):
          
          return normalized_mutual_info_score(self.get_labels(self), self.get_labels(reference_clusters))
docs: Calculates the normalized mutual information w.r.t. the reference clusters (explicit evaluation)
  
          :param reference_clusters: Clusters that are to be used as reference
          :return: The resulting normalized mutual information score.