code: def term_doc_lists(self):
          '''
          Returns
          -------
          dict
          '''
          doc_ids = self._X.transpose().tolil().rows
          terms = self._term_idx_store.values()
          return dict(zip(terms, doc_ids)f term_doc_lists(self):
          '''
          Returns
          -------
          dict
          '''
          doc_ids = self._X.transpose().tolil().rows
          terms = self._term_idx_store.values()
          return dict(zip(terms, doc_ids))
docs: Returns
          -------
          dict