anchor.diff:      }
       Completer<int> __completer = __nextBookmark.completer;
       if (__prevBookmark == null) {
  -      __nextBookmark.variables["value"] = value;
  +      __nextBookmark.variables[__valueRef] = value;
       }
       try {
   
  
positive.code:  *   }
  */
  Future<int> simpleStatement(int value) {
  
    Future<int> _simpleStatement(Bookmark __prevBookmark, int value) {
      Bookmark __nextBookmark = new Bookmark<int>();
  
negative.code:  *   }
   */
  Future<int> whileLoop(int value) {
    const __valueRef = ":value";
  
    Future<int> _whileLoop(Bookmark __prevBookmark, int value) {
      Bookmark __nextBookmark = new Bookmark<int>();
  