anchor.diff:        closed = true;
         c.close();
       });
  -    
  +
       return c.stream;
     }
   }
  
positive.code: /// metadata about the entity (Entity.streamy) to be inaccurate, but will
  /// prevent multiple values from being published on [Stream]s when core [Entity]
  /// data has not changed.
  class EntityDedupTransformer<T extends Entity>
      extends StreamEventTransformer<T, T> {
    var _last = null;
  
    handleData(T data, EventSink<T> sink) {
      if (!Entity.deepEquals(data, _last)) {
        sink.add(data);
      }
      _last = data;
    }
  }
  
  
negative.code: 
  /// Represents a request that was issued, and allows listening for its completion.
  class TrackedRequest {
  
    /// Request that was issued.
    final Request request;
  
    /// A future that completes before the first response for the request is returned
    /// (may be an error).
    final Future beforeFirstResponse;
  
    /// A future that completes when the first response for the request is returned
    /// (may be an error).
    final Future onFirstResponse;
  
    TrackedRequest._private(this.request, this.beforeFirstResponse, this.onFirstResponse);
  }
  
  /// Provides a global notification of when requests are issued and when they receive
  /// their first response.
  class RequestTrackingTransformer extends RequestStreamTransformer {
  
    final _controller = new StreamController<TrackedRequest>.broadcast(sync: true);
  
    Stream<TrackedRequest> get trackingStream => _controller.stream;
  
    RequestTrackingTransformer();
  
    Stream bind(Request request, Stream responseStream) {
      var sub;
      var preCallbackCompleter = new Completer.sync();
  