next_output_index, dtype);

  std::vector<NodeBuilder::NodeOut> input_list({enter_input, next_input});
  const string unique_name = scope.GetUniqueNameForOp("Merge");
  NodeBuilder builder = NodeBuilder(unique_name, "Merge").Input(input_list);
  scope.UpdateBuilder(&builder);

  Node* merge_node;
  TF_RETURN_IF_ERROR(builder.Finalize(scope.graph(), &merge_node));