anchor.diff:    final _httpBodyExtractor;
   
     /**
  +   * Default handler for NotFoundView.
  +   */
  +  RequestHandler _notFoundViewHandler = (Request request) {
  +    request.response
  +      ..statusCode = HttpStatus.NOT_FOUND
  +      ..close();
  +  };
  +
  +  /**
      * Constructor.
      */
     Backend.config(this._server, this.router, this._requestNavigator,
  -      this._hmacFactory, this._httpBodyExtractor);
  +    this._hmacFactory, this._httpBodyExtractor) {
  +    _requestNavigator.registerDefaultHandler((httpRequest, urlParams)
  +      => prepareRequestHandler(httpRequest, urlParams, _notFoundViewHandler));
  +  }
   
     /**
      * Creates a new backend.
  
positive.code: 
    /**
     * If nothing is matched then try to add a slash on end and redirect. If still
     * not then handler will be called.
     */
    void addNotFoundView(RequestHandler handler) {
      _requestNavigator.registerDefaultHandler((httpRequest, urlParams) {
        var uri = httpRequest.uri;
        if (!uri.path.endsWith('/')) {
          httpRequest.response.redirect(new Uri(
            scheme: uri.scheme,
            host: uri.host,
            port: uri.port,
  
negative.code:         ));
        }
        else{
          handler(request);
        }
      });
    }
  