code: def words(self, fileids=None) -> Generator[str, str, None]:
          
          for sentence in self.sents(fileids):
              words = self._word_tokenizer.tokenize(sentence)
              for word in words:
                  yield word
docs: Provide the words of the corpus; skipping any paragraphs flagged by keywords to the main
          class constructor
          :param fileids:
          :return: words, including punctuation, one by one