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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 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