def __init__(self, inf, fetches, size):
            """
            Args:
                size(int): number of tensors to fetch per tower
            """
            super(DataParallelInferenceRunner._InferencerToHookDataParallel, self).__init__(inf, fetches)
            assert len(self._fetches) % size == 0
            self._sz = size

            Args:
                size(int): number of tensors to fetch per tower
            
tensorpack/callbacks/inference_runner.py