def ReadResponsesForRequestId(self, session_id, request_id, timestamp=None):
    """Reads responses for one request.

    Args:
      session_id: The session id to use.
      request_id: The id of the request.
      timestamp: A timestamp as used in the data store.

    Yields:
      fetched responses for the request
    """
    request = rdf_flow_runner.RequestState(id=request_id, session_id=session_id)
    for _, responses in self.ReadResponses([request], timestamp=timestamp):
      return responses