anchor.diff:        return true;
       }
       return false;
  +  }
  +
  +  void addError(Object error, [StackTrace stackTrace]) {
  +    _controller.addError(error, stackTrace);
     }
   
     void cancel() {
  
positive.code:           }
          });
        });
      });
  
      return controller.stream;
  
negative.code:         if (!topicsToReset.containsKey(result.topicName)) {
            topicsToReset[result.topicName] = [];
          }
          topicsToReset[result.topicName].add(result.partitionId);
        }
      }
  
  