code: def load_stream(self, stream):
          
          # load the batches
          for batch in self.serializer.load_stream(stream):
              yield batch
  
          # load the batch order indices
          num = read_int(stream)
          batch_order = []
          for i in xrange(num):
              index = read_int(stream)
              batch_order.append(index)
          yield batch_order
docs: Load a stream of un-ordered Arrow RecordBatches, where the last iteration yields
          a list of indices that can be used to put the RecordBatches in the correct order.