// and `return_value_from_device`, it is safe to access return_operand_map and
  // call `front()` method.
  for (const auto& return_val : return_value_from_host) {
    order_from_new_output_to_previous_output.push_back(
        return_operand_map[return_val].front());
    return_operand_map[return_val].pop_front();
  }

  for (const Value& return_val : return_value_from_device) {