anchor.diff:    }
   
     void printEvent(String name) {
  -    for (Object o in stack) {
  +    for (Object o in stack.values) {
         String s = "  $o";
         int index = s.indexOf("\n");
         if (index != -1) {
  
positive.code: // BSD-style license that can be found in the LICENSE file.
  
  library fasta.stack_listener;
  
  import 'dart:collection' show Queue;
  
  import 'package:front_end/src/fasta/parser.dart' show ErrorKind, Listener;
  
  
negative.code: 
    List popList(int n) {
      if (n == 0) return null;
      return stack.popList(n);
    }
  
    void debugEvent(String name) {
  