def result(self, timeout=None):
        """If the operation succeeded, return its result.  If it failed,
        re-raise its exception.

        This method takes a ``timeout`` argument for compatibility with
        `concurrent.futures.Future` but it is an error to call it
        before the `Future` is done, so the ``timeout`` is never used.
        """
        self._clear_tb_log()
        if self._result is not None:
            return self._result
        if self._exc_info is not None:
            try:
                raise_exc_info(self._exc_info)
            finally:
                self = None
        self._check_done()
        return self._result
If the operation succeeded, return its result.  If it failed,
        re-raise its exception.

        This method takes a ``timeout`` argument for compatibility with
        `concurrent.futures.Future` but it is an error to call it
        before the `Future` is done, so the ``timeout`` is never used.