code: function(req) {
          var args = utils.arg2arr(arguments), index = -1;
          var allHandlers = this._handlers.concat(this._lastHandlers);
          var next = function(error) {
              var item = allHandlers[++index];
              if (item) {
                  var matched = false;
                  if (utils.isString(item.routeExp)) {
                      matched = req.url.indexOf(item.routeExp) === 0;
                  } else if (utils.type(item.routeExp) === 'regexp') {
                      matched = item.routeExp.test(parse(req.url).pathname);
                  }
                  //
                  if (matched) {
                      var clone = args.concat();
                      if (error) { clone.push(error); }
                      item.handler.apply(null, clone);
                  }
              }
          };
          args.push(next);
          next();
      }
docs: /*
  execute the handlers in the format as:
  function(req, [args], next, error) { }
  function(req, res, next, error) { next(error); }