// grad(x) = grad(y) * conj(dy/dx)
  grad_outputs->push_back(
      Mul(scope, grad_inputs[0], ConjugateHelper(scope, dydx)));
  return scope.status();
}
REGISTER_GRADIENT_OP("Expm1", Expm1Grad);

Status LogGrad(const Scope& scope, const Operation& op,
               const std::vector<Output>& grad_inputs,
               std::vector<Output>* grad_outputs) {
  // y = log(x)
  // dy/dx = 1 / x

    const float const0_val[] = {1.0, 2.0, 3.0, 4.0};
    TF_Operation* const0 = FloatConst2x2(graph_, s_, const0_val, "Const_0");
    TF_Operation* nograd = NoGradientOp(graph_, s_, const0, "NoGrad");
    inputs[0] = TF_Output{const0, 0};
    outputs[0] = TF_Output{nograd, 0};
    EXPECT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);
  }

  void BuildSuccessGraph(TF_Output* inputs, TF_Output* outputs) {