const string unique_suffix = absl::StrCat("_", GetUniqueScopeId());

  std::vector<Node*> starts;
  starts.push_back(start);
  auto enter = [&](Node* n) { AddOrAppendXlaInternalScope(n, unique_suffix); };
  ReverseDFSFrom(*graph_, starts, enter, /*leave=*/nullptr,
                 /*stable_comparator=*/NodeComparatorName());
}

void ClusterScopingPassImpl::AddScopeToAllTransitiveSuccessors(Node* start) {

  absl::flat_hash_set<const Node*> guaranteed_const_nodes;
  std::vector<const Node*> srcs;
  srcs.reserve(src_arg_pairs.size());
  for (const auto& src_arg : src_arg_pairs) {
    srcs.push_back(src_arg.first);
  }
  ReverseDFSFrom(
      graph, srcs, /*enter=*/nullptr,
      /*leave=*/[&guaranteed_const_nodes](const Node* n) {
        // TODO(vinuraja): Doesn't work in the presence of loops.