code: def _recursive_hypernyms(self, hypernyms):   
          
          hypernyms |= set(self.hypernyms())
  
          for synset in self.hypernyms():
              hypernyms |= synset._recursive_hypernyms(hypernyms)
          return hypernyms
docs: Finds all the hypernyms of the synset transitively.
  
          Notes
          -----
            Internal method. Do not call directly.
  
          Parameters
          ----------
            hypernyms : set of Synsets
          An set of hypernyms met so far.
  
          Returns
          -------
            set of Synsets
          Returns the input set.