code: def _count_words(self, words):
          
          bonus_words_count = 0
          stigma_words_count = 0
  
          for word in words:
              if word in self._bonus_words:
                  bonus_words_count +=1
              if word in self._stigma_words:
                  stigma_words_count += 1
  
          return bonus_words_count, stigma_words_count
docs: Counts number of bonus/stigma words.
  
          :param iterable words:
              Collection of words.
          :returns pair:
              Tuple with number of words (bonus words, stigma words).