std::shared_ptr<NameMap> name_map_ = nullptr;
  std::shared_ptr<ShapeRefiner> refiner_ = nullptr;

  // If scope_used_ is not nullptr, op_name_ should be empty and
  // GetUniqueNameForOp can only be called once on this scope. More calls to
  // GetUniqueNameForOp will cause an error status to be set on this scope.
  std::shared_ptr<bool> scope_used_ = nullptr;

  const std::vector<Operation> control_deps_;

                                  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));