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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 sync_streams(self):
 """ Access the sync_streams :returns: twilio.rest.sync.v1.service.sync_stream.SyncStreamList :rtype: twilio.rest.sync.v1.service.sync_stream.SyncStreamList """

        if self._sync_streams is None:
            self._sync_streams = SyncStreamList(self._version, service_sid=self._solution['sid'], )
        return self._sync_streams