// and string consistent.
  forward_op_->attrs.BuildNodeDef();
  std::unique_ptr<GradientFunction> gradient_fn;
  TF_RETURN_IF_ERROR(registry.Lookup(*forward_op_, &gradient_fn));
  tape->RecordOperation(forward_op_->inputs, retvals, gradient_fn.release(),
                        op_->Name());
  return absl::OkStatus();
}
}  // namespace internal

}  // namespace gradients