docs: def _expect_empty(self):
          """ Checks if the token stream is empty.
  
              * Raises a ``ParseError` exception if a token is found.
              """
  
          item = self._lexer.get_token()
          if item:
              line_no, token = item
              raise ParseError(u"Unexpected token '{0}' on line {1}"
                               .format(common.from_utf8(token.strip()), line_no))