return ops::Switch(root.WithOpName(prefix + "/switch"), value, predicate);
}

TensorId ControlOutputFor(const Output& o) {
  return {o.node()->name(), Graph::kControlSlot};
}

void VLogGraphIfAsked(const Graph& graph) {
  if (VLOG_IS_ON(3)) {
    GraphDef graph_def;
    graph.ToGraphDef(&graph_def);
    string serialized;
    ::tensorflow::protobuf::TextFormat::PrintToString(graph_def, &serialized);