anchor.diff:  
   
   
  -  void checkPassword(){
  +  Future<Null> checkPassword() async{
       ////;
       numSimulationsDone = 0; //but don't reset stats
       sessionSummariesDisplayed = [];
  
positive.code: void main() {
    doNotRender = true;
    rand = new Random();
    querySelector("#pw_hint_button").onClick.listen((e) => self.showHint());
    querySelector("#pwButton").onClick.listen((e) => self.checkPassword());
    window.onError.listen((Event event){
  
negative.code:       window.alert("Hrrrm...let me think about it.");
        initial_seed = tmp;
        curSessionGlobalVar = new Session(SimController.instance.initial_seed);
        startSessionThenSummarize();
      }
    }
  
  