int cycles_graph_node_id, bool* found_unclustered) {
  Cluster* cluster = GetClusterForCyclesGraphNode(cycles_graph_node_id);
  if (cluster) {
    return cluster->DebugString(*graph_);
  }

  *found_unclustered = true;
  if (cycles_graph_node_id >= graph_->num_node_ids()) {
    return absl::StrCat("<oob #", cycles_graph_node_id, ">");
  }