def FetchResponses(self, session_id):
    """Retrieves responses for a well known flow.

    Args:
      session_id: The session_id to get the requests/responses for.

    Yields:
      The retrieved responses.
    """
    timestamp = (0, self.frozen_timestamp or rdfvalue.RDFDatetime.Now())

    for response in self.data_store.FetchResponsesForWellKnownFlow(
        session_id, self.response_limit, timestamp=timestamp):
      yield response