Output identity = ops::Identity(s.WithOpName("identity_true_fn"), arg);
    ops::_Retval retval(s.WithOpName("retval"), identity, 0);
    std::unique_ptr<Graph> g(new Graph(OpRegistry::Global()));
    TF_CHECK_OK(s.ToGraph(g.get()));
    auto node_name_image = g->BuildNodeNameIndex();
    node_name_image["identity_true_fn"]->AddAttr("_oc", "0");
    PartialTensorShape shape({2});