anchor.diff:  }
   
   /**
  - * Used to mark scope entry which logs single argument.
  + * Used to mark scope entry which logs single argument. The return value is used
  + * to leave the scope again. Arguments only work if WTF has been enabled.
    */
   dynamic enter1(scope, arg1) {
     if (wtfEnabled) {
  
positive.code: }
  
  /**
   * Used to mark scope exit with a value
   */
  dynamic leaveVal(scope, returnValue) {
    if (wtfEnabled) {
      _arg2[0] = scope;
      _arg2[1] = returnValue;
  
negative.code:   return null;
  }
  
  /**
   * Ends a async operation. [range] is the return value from [startAsync].
   * Async ranges only work if WTF has been enabled.
   */
  void endAsync(dynamic range) {
    if (wtfEnabled) {
      _arg1[0] = range;
      _endTimeRange.apply(_arg1, thisArg: _trace);
    }
    return null;
  }
  