}

  void VerifyCollocation(TF_Operation* op,
                         const std::vector<std::string>& expected) {
    TF_AttrMetadata m =
        TF_OperationGetAttrMetadata(op, tensorflow::kColocationAttrName, s_);
    if (expected.empty()) {
      ASSERT_EQ(TF_INVALID_ARGUMENT, TF_GetCode(s_)) << TF_Message(s_);
      EXPECT_EQ("Operation 'add' has no attr named '_class'.",

      if (count < max_control_outputs) {
        control_outputs[count] = ToOperation(edge->dst());
      }
      ++count;
    }
  }
  return count;
}

TF_AttrMetadata TF_OperationGetAttrMetadata(TF_Operation* oper,
                                            const char* attr_name,
                                            TF_Status* status) {
  TF_AttrMetadata metadata;