docs: def result(self, timeout=None):
          """Enters polling loop on OperationsClient.get_operation, and once
          Operation.done is true, then returns Operation.response if successful or
          throws GaxError if not successful.
  
          This method will wait up to timeout seconds. If the call hasn't
          completed in timeout seconds, then a RetryError will be raised. timeout
          can be an int or float. If timeout is not specified or None, there is no
          limit to the wait time.
          """
          # Check exceptional case: raise if no response
          if not self._poll(timeout).HasField('response'):
              raise GaxError(self._operation.error.message)
  
          # Return expected result
          return _from_any(self._result_type, self._operation.response)