docs: def _delete_text_ngrams(self, text_id):
          """Deletes all n-grams associated with `text_id` from the data
          store.
  
          :param text_id: database ID of text
          :type text_id: `int`
  
          """
          with self._conn:
              self._conn.execute(constants.DELETE_TEXT_NGRAMS_SQL, [text_id])
              self._conn.execute(constants.DELETE_TEXT_HAS_NGRAMS_SQL, [text_id])