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: }
  
  abstract class StackListener extends Listener {
    final Queue<Object> stack = new Queue<Object>();
  
    Uri get uri;
  
  
negative.code:   @override
    void logEvent(String name) {
      internalError("Unhandled event: $name in $runtimeType $uri:\n"
          "  ${stack.values.join('\n  ')}");
    }
  
    @override
  