code: function cookie(req, res, next){
    // cookie getter
    req.cookies = Cookie.parse(req.headers['cookie']);
    /**
     * [function cookie setter]
     * @param  {[type]} key   [description]
     * @param  {[type]} value [description]
     * @param  {[type]} attrs [description]
     * @return {[type]}       [description]
     */
    res.cookie = function(key, value, attrs = {}){
      if(value === null) { attrs.expires = new Date(0); value = ''; }
      res.setHeader('Set-Cookie', Cookie(key, value, attrs).toHeader());
    };
    next();
  }
docs: [function cookie]
  @param  {[type]}   req  [request]
  @param  {[type]}   res  [response]
  @param  {Function} next [call next middleware]