anchor.diff:  
     }
   
  +  String getQuipAboutSession(SessionSummary sum) {
  +    throw "todo";
  +  }
  +
     void printStats() {
  +    throw "todo";
   
     }
   
  
positive.code:     numSimulationsDone ++;
      initial_seed = curSessionGlobalVar.rand.nextInt(); //child session
      if(numSimulationsDone >= numSimulationsToDo){
        querySelector("#button").prop('disabled', false);
  
            window.alert("Notice: should be ready to check more sessions.");
          querySelector("input[name='filter']").each((){;
          querySelector(this).prop('disabled', false);
          });
      }else{
        //TODO used to have a timeout here, do i really need to?
  
negative.code: 
      SessionSummary sum = curSessionGlobalVar.generateSummary();
      if(nonRareSessionCallback) return nonRareSessionCallback(sum); //it will handle calling next session.
      querySelector("#story").setInnerHtml("");
      allSessionsSummaries.add(sum);
      sessionSummariesDisplayed.add(sum);
      //printSummaries();  //this slows things down too much. don't erase and reprint every time.
  