anchor.diff:  }
   
   main() {
  +  asyncStart();
     testMultiController();
     testSingleController();
     testExtraMethods();
  
positive.code:   asyncStart();
    asyncStart();
    StreamController c2 = new StreamController(onCancel: () {
      asyneEnd();
      throw "ERROR2";
    });
    c2.add(1);
  
negative.code: void testCancelThrow() {
    asyncStart();
    asyncStart();
    asyncStart();
    StreamController c = new StreamController(onCancel: () {
      asyncEnd();
      throw "ERROR";
  