anchor.diff:          trace.record(new RequestOverEvent());
           _sentDone = true;
         }
  -    });
  +    }, trace);
     }
   
     void handleError(error, EventSink<Response> sink, Trace trace) {
  
positive.code:         trace.record(new RequestOverEvent());
          _sentDone = true;
        }
      });
    }
  
    void handleDone(EventSink<Response> sink, Trace trace) {
  
negative.code:   const UserCallbackDoneEvent._private();
  
    String toString() => 'streamy.userCallback.done';
  }
  
  class UserCallbackAsyncEnterEvent implements TraceEvent {
    factory UserCallbackAsyncEnterEvent() => const UserCallbackAsyncEnterEvent._private();
  
    const UserCallbackAsyncEnterEvent._private();
  
    String toString() => 'streamy.userCallback.async.start';
  }
  
  class UserCallbackAsyncExitEvent implements TraceEvent {
    factory UserCallbackAsyncExitEvent() => const UserCallbackAsyncExitEvent._private();
  
    const UserCallbackAsyncExitEvent._private();
  
    String toString() => 'streamy.userCallback.async.done';
  }
  
  /// Fired when the response [Stream] has terminated.
  