const auto &init_values_ty = op.getInitValues().getType();
  int n_init_values = init_values_ty.size();
  if (n_init_values != n_inputs) {
    return op.emitOpError() << "Number of inputs (" << n_inputs
                            << ") is different than number of init_values ("
                            << n_init_values << ")";
  }

  auto input_ty_0 = inputs_ty[0].cast<ShapedType>();

Status ComputeGradientError(const Scope& scope, const Output& x,
                            const Tensor& x_init_value, const Output& y,
                            const TensorShape& y_shape, JAC_T* max_error) {
  // Initialize 'x_data' from 'x_init_value'.
  std::vector<Tensor> x_datas(1, Tensor(x_init_value));
  // Compute gradient error.
  return ComputeGradientErrorInternal<X_T, Y_T, JAC_T>(

// set of values. Returns the final set of values via `final_values`. The
// initial set of values is passed in via `init_values`.
//
// This effectively does:
//
// ```c++
// SmallVector<Values, 4> old_values = init_values;
// SmallVector<Values, 4> new_values;
// for (int i = 0; i < num_iterations; ++i) {
//   body_fn(old_values, &new_values, ...);
//   old_values = new_values;

  }];

  let arguments = (ins
    Arg<Variadic<TF_Tensor>, [{the input tensor(s)}]>:$inputs,
    Arg<Variadic<TF_Tensor>, [{scalar initial value(s) for the reduction}]>:$init_values,

    I64ArrayAttr:$dimensions_to_reduce,
    SymbolRefAttr:$reducer
  );

  let results = (outs
    Variadic<TF_Tensor>:$outputs
  );