code: def stream(self, timeout=None):
          
          query, lrf = self._normalize_query()
          return self._client.stream_mapred(self._inputs, query, timeout)
docs: Streams the MapReduce query (returns an iterator). Shortcut
          for :meth:`riak.client.RiakClient.stream_mapred`.
  
          :param timeout: Timeout in milliseconds
          :type timeout: integer
          :rtype: iterator that yields (phase_num, data) tuples