docs: function end(res, code) {
    if (code >= 400) {
      // check res object contains connect/express request and next structure
      if (res.req && res.req.next) {
        var error = new Error(http.STATUS_CODES[code]);
        error.status = code;
        return res.req.next(error);
      }
  
      // write human-friendly error message
      res.writeHead(code);
      res.end('[' + code + '] ' + http.STATUS_CODES[code]);
      return;
    }
  
    // just end with no body for 304 responses and such
    res.writeHead(code);
    res.end();
  }