anchor.diff:    });
   }
   
  +var longS = new List.filled(1000, 'a').join('');
  +
   test3(){
  -  var longS ='aaaaaaaaaaaabbbbbbbbbbcccccc';
       Map m = new Map.from({'a': {'a': longS, 'b': {'a' : longS, 'b': longS}}});
       for(int i=0; i<10000000000; i++){
         print(i);
  
positive.code: import "package:unittest/unittest.dart";
  import 'package:clean_data/clean_data.dart';
  import "dart:async";
  
  magicalTick(){
    new Timer.periodic(const Duration(milliseconds:1000), (t) {
  
negative.code: var data;
  
  /*
   * enhance 8 level, 4 fork: 16s, 9s, 2.9s
   */
  
  test1(){
  