*(f_lib_proto.add_function()) = test::function::XTimesTwo();

  // Construct a graph:
  //   A = Placeholder[dtype=int32]
  //   B = XTimesTwo[_tpu_replicate="cluster"](A)
  //   C = XTimesTwo[_xla_compile_id="cluster"](A)
  TF_ASSERT_OK(scope_.graph()->AddFunctionLibrary(f_lib_proto));

  Output x = Placeholder(scope_, DT_FLOAT);
  NameAttrList f;
  f.set_name("XTimesTwo");
  (*f.mutable_attr())["T"].set_type(DT_FLOAT);