code: def wup_similarity(self, target_synset):
          
          lchs = self.lowest_common_hypernyms(target_synset)
          lcs_depth = lchs[0]._min_depth() if lchs and len(lchs) else None
          self_depth = self._min_depth() 
          other_depth = target_synset._min_depth()
          if lcs_depth is None or self_depth is None or other_depth is None: 
              return None 
  
          return (2.0 * lcs_depth) / (self_depth + other_depth)
docs: Calculates Wu and Palmer's similarity between the two synsets.
          
          Notes
          -----
            Similarity is calculated using the formula ( 2*depth(least_common_subsumer(synset1,synset2)) ) / ( depth(synset1) + depth(synset2) )
          
          Parameters
          ----------
            synset : Synset
          Synset from which the similarity is calculated.
          
          Returns
          -------
            float
          Wu and Palmer's similarity from `synset`.