g->mu.unlock();
  if (del) delete g;
}

TF_Operation* TF_GraphOperationByName(TF_Graph* graph, const char* oper_name) {
  mutex_lock l(graph->mu);
  auto iter = graph->name_map.find(oper_name);
  if (iter == graph->name_map.end()) {
    return nullptr;
  } else {
    return ToOperation(iter->second);
  }
}

TF_Operation* TF_GraphNextOperation(TF_Graph* graph, size_t* pos) {

	var (
		idx              int
		inName           bool
		afterParenthesis bool
		namedMap         = make(map[string]interface{}, len(expr.Vars))
	)

	for _, v := range expr.Vars {
		switch value := v.(type) {
		case sql.NamedArg:
			namedMap[value.Name] = value.Value
		case map[string]interface{}:
			for k, v := range value {
				namedMap[k] = v
			}
		default:
			var appendFieldsToMap func(reflect.Value)