digraph G {
  subgraph cluster1 {
    label = "induction";
    351 -> 352;
    351 -> 353;
    352 -> 358;
    subgraph cluster2 {
      label = "base case";
      358;
    }
    353 -> 367;
    subgraph cluster3 {
      label = "step case";
      367 -> 368;
      368 -> 370;
      370 -> 372;
      372 -> 374;
      374 -> 376;
      376 -> 378;
    }
  }
  344 -> 345;
  345 -> 351;
}