// The scalar const oper also has a consumer.
  ASSERT_EQ(1, TF_OperationOutputNumConsumers(TF_Output{three, 0}));
  TF_Input three_port;
  EXPECT_EQ(1,
            TF_OperationOutputConsumers(TF_Output{three, 0}, &three_port, 1));
  EXPECT_EQ(add, three_port.oper);
  EXPECT_EQ(1, three_port.index);

  // Serialize to GraphDef.
  GraphDef graph_def;
  ASSERT_TRUE(GetGraphDef(graph, &graph_def));