anchor.diff:      return pipeline.addHandler(_handle);
     }
   
  -  shelf.Middleware _conditionalMiddleware(shelf.Middleware middleware) {
  +  shelf.Middleware _conditionalMiddleware(middleware) {
       return (shelf.Handler innerHandler) {
         return (shelf.Request request) {
           if (_shouldUseMiddlewareForRequest(request, middleware))
  -          return middleware(innerHandler)(request);
  +          return _createMiddleware(middleware)(innerHandler)(request);
           return innerHandler(request);
         };
       };
  
positive.code:   var _highPriorityMiddleware = 0;
  
    void addMiddleware(Object middleware, {bool highPriority: false}) {
      shelf.Middleware shelfMiddleware = _createMiddleware(middleware);
      if (highPriority) return _middleware.insert(
          _highPriorityMiddleware++, shelfMiddleware);
      _middleware.add(shelfMiddleware);
    }
  
    shelf.Middleware _createMiddleware(Object middleware) {
  
negative.code:   HttpServer _server;
    String _host;
    int _port;
    List _middleware = new List();
    Container _container;
    Config _config;
    _ResponseMapper _responseMapper;
  