code: def term_count_buckets(self):
  
          
  
          buckets = {}
          for term, count in self.term_counts().items():
              if count in buckets: buckets[count].append(term)
              else: buckets[count] = [term]
  
          return buckets
docs: Returns:
              dict: A dictionary that maps occurrence counts to the terms that
              appear that many times in the text.