// 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");

// Set the prefix to be prepended to the names of nodes in `graph_def` that will
// be imported into `graph`. `prefix` is copied and has no lifetime
// requirements.
TF_CAPI_EXPORT extern void TF_ImportGraphDefOptionsSetPrefix(
    TF_ImportGraphDefOptions* opts, const char* prefix);

// Set the execution device for nodes in `graph_def`.
// Only applies to nodes where a device was not already explicitly specified.

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,