int64_t tensor_id = source_tensor_ids[i];
    auto grad_it = gradients.find(tensor_id);
    if (grad_it == gradients.end()) {
      result[i] = nullptr;
    } else {
      if (grad_it->second.size() > 1) {
        Gradient* grad = vspace.AggregateGradients(grad_it->second);
        grad_it->second.clear();
        grad_it->second.push_back(grad);
      }
      result[i] = grad_it->second[0];
      used_gradient_ids.insert(tensor_id);

 public:
  Status Compute(AbstractContext* ctx,
                 absl::Span<AbstractTensorHandle* const> grad_outputs,
                 absl::Span<AbstractTensorHandle*> grad_inputs) override {
    CHECK_EQ(grad_outputs.size(), 1);
    CHECK_EQ(grad_inputs.size(), 1);
    grad_inputs[0] = grad_outputs[0];
    if (grad_inputs[0]) {
      grad_inputs[0]->Ref();
    }
    return absl::OkStatus();
  }
};

// Computes:
//

    float* expected_grad, int num_grad, bool use_function,
    double abs_error = 1e-2) {
  Status s;
  AbstractTensorHandlePtr numerical_grad;
  {
    AbstractTensorHandle* numerical_grad_raw;
    s = CalcNumericalGrad(ctx, model, inputs, input_index, use_function,
                          &numerical_grad_raw);
    ASSERT_EQ(errors::OK, s.code()) << s.message();

    TF_DeleteStatus(s_);
  }

  void TestGradientsSuccess(bool grad_inputs_provided) {
    TF_Output inputs[2];
    TF_Output outputs[1];
    TF_Output grad_outputs[2];
    TF_Output expected_grad_outputs[2];

    BuildSuccessGraph(inputs, outputs);
    BuildExpectedGraph(grad_inputs_provided, expected_grad_outputs);

    AddGradients(grad_inputs_provided, nullptr, inputs, 2, outputs, 1,

//  public:
//   Status Compute(Context* ctx,
//                  absl::Span<AbstractTensorHandle* const> grad_inputs,
//                  absl::Span<AbstractTensorHandle*> grad_outputs) override {
//     grad_outputs[0] = grad_inputs[0];
//     grad_outputs[1] = grad_inputs[0];
//     grad_outputs[0]->Ref();
//     grad_outputs[1]->Ref();
//     return OkStatus();
//   }
//   ~AddGradientFunction() override {}
// };
//

    TF_Tensor* grad_tensor;
    TF_RETURN_IF_ERROR(GetValue(diff_quotient.get(), &grad_tensor));
    float grad_data[1];
    memcpy(&grad_data[0], TF_TensorData(grad_tensor),
           TF_TensorByteSize(grad_tensor));
    TF_DeleteTensor(grad_tensor);
    dtheta_approx[i] = grad_data[0];
  }

  // Populate *numerical_grad with the data from dtheta_approx.

EAAI2C,EAAK3C,IACrBa,EAAO2N,KAAM1N,EAAU2X,EAAMzY,GAAK4B,GAGnC,OAAa,EAANe,EAAU9B,EAAOqP,WAAYtO,GAAQA,GAE7C0M,OAAQ,SAAUxN,GACjB,OAAOjD,KAAK6D,UAAW6W,EAAQ1a,KAAMiD,GAAY,IAAI,KAEtD8R,IAAK,SAAU9R,GACd,OAAOjD,KAAK6D,UAAW6W,EAAQ1a,KAAMiD,GAAY,IAAI,KAEtDoX,GAAI,SAAUpX,GACb,QAASyX,EACR1a,KAIoB,iBAAbiD,GAAyBuX,EAAc/M,KAAMxK,GACnDD,EAAQC,GACRA,GAAY,IACb,GACCK,UASJ,IAAIuX,EAMH1P,EAAa,uCAENnI,EAAOG,GAAGC,KAAO,SAAUH,EAAUC,EAASqS,GACpD,IAAIzI,EAAOzI,EAGX,IAAMpB,EACL,OAAOjD,KAQR,GAHAuV,EAAOA,GAAQsF,EAGU,iBAAb5X...

EAAI2C,EAAK3C,IACrBa,EAAO2N,KAAM1N,EAAU2X,EAAMzY,GAAK4B,GAGnC,OAAa,EAANe,EAAU9B,EAAOqP,WAAYtO,GAAQA,GAE7C0M,OAAQ,SAAUxN,GACjB,OAAOjD,KAAK6D,UAAW6W,EAAQ1a,KAAMiD,GAAY,IAAI,KAEtD8R,IAAK,SAAU9R,GACd,OAAOjD,KAAK6D,UAAW6W,EAAQ1a,KAAMiD,GAAY,IAAI,KAEtDoX,GAAI,SAAUpX,GACb,QAASyX,EACR1a,KAIoB,iBAAbiD,GAAyBuX,EAAc/M,KAAMxK,GACnDD,EAAQC,GACRA,GAAY,IACb,GACCK,UASJ,IAAIuX,EAMH1P,EAAa,uCAENnI,EAAOG,GAAGC,KAAO,SAAUH,EAAUC,EAASqS,GACpD,IAAIzI,EAAOzI,EAGX,IAAMpB,EACL,OAAOjD,KAQR,GAHAuV,EAAOA,GAAQsF,EAGU,iBAAb5X...

  // Define the function and its grad
  DefineFunction(func_name_, &func_);
  TF_Function* grad_func;
  DefineFunction("MyGrad", &grad_func);

  // Add func and its gradient to host graph
  TF_GraphCopyFunction(host_graph_, func_, grad_func, s_);

  ASSERT_EQ(TF_OK, TF_GetCode(s_)) << TF_Message(s_);

  TF_DeleteFunction(grad_func);

  const StackTracesMap* func_stack_traces;

        "yellow":      "#ffec3d",
        "amber":       "#ffc105",
        "orange":      "#ffa724",
        "deep-orange": "#ff6e42",
        "brown":       "#795649",
        "grey":        "#757575",
        "blue-grey":   "#546d78",
        "black":       "#000000",
        "white":       "#ffffff"
      }[primary] or "#4051b5" }}
    {%- endif -%}

  # Text color (default: white)
  - &color >-