// Import it, with a prefix, in a fresh graph.
  TF_DeleteGraph(graph);
  graph = TF_NewGraph();
  TF_ImportGraphDefOptions* opts = TF_NewImportGraphDefOptions();
  TF_ImportGraphDefOptionsSetPrefix(opts, "imported");
  TF_GraphImportGraphDef(graph, graph_def, opts, s);
  ASSERT_EQ(TF_OK, TF_GetCode(s)) << TF_Message(s);

  TF_Operation* scalar = TF_GraphOperationByName(graph, "imported/scalar");

TF_ImportGraphDefOptions* TF_NewImportGraphDefOptions() {
  return new TF_ImportGraphDefOptions;
}
void TF_DeleteImportGraphDefOptions(TF_ImportGraphDefOptions* opts) {
  delete opts;
}
void TF_ImportGraphDefOptionsSetPrefix(TF_ImportGraphDefOptions* opts,
                                       const char* prefix) {
  opts->opts.prefix = prefix;
}
void TF_ImportGraphDefOptionsSetDefaultDevice(TF_ImportGraphDefOptions* opts,