GraphDef def;
  {
    mutex_lock l(graph->mu);
    graph->graph.ToGraphDef(&def);
  }
  status->status = MessageToBuffer(def, output_graph_def);
}

void TF_GraphGetOpDef(TF_Graph* graph, const char* op_name,
                      TF_Buffer* output_op_def, TF_Status* status) {
  const OpDef* op_def;
  {
    mutex_lock l(graph->mu);