!7

cprint {
  class State extends ProbabilisticMachine2.State {
    Runnable continuation;

    public State makeDescendant() {
      new State s;
      prepareDescendant(s);
      s.continuation = continuation;
      ret s;
    }
    
    void doneWithSubroutine {
      if (continuation == null) ret;
      State s = makeDescendant();
      s.continuation = null;
      switchTo(s);
      continuation.run();
    }
    
    void step {
      doneWithSubroutine();
    }
  }
  
  start-thread {
    new ProbabilisticMachine2<State> pm;
    State s = new {
      run {
        print("Hello");
        doneWithSubroutine();
      }
    };
    s.continuation = r {
      print("World");
    };
    pm.addState(s);

    pm.onRunningState = st -> {
      print("Running state " + st);
    };
    pm.onRanState = st -> {
      print("Ran state " + st);
    };
    stepAllWithStats(pm);
  }
}