code: function redirectCookiesWith(data) {
          var uri = URL.parse(data.url, true); // true = parseQueryString
          if (uri.query[REDIRECT_QUERY_PARAM]) {
              var nextUri = URL.parse(uri.query[REDIRECT_QUERY_PARAM]);
              debug('copying cookies from %s to %s', data.url, uri.query[REDIRECT_QUERY_PARAM]);
              var cookies = libCookie.parse(data.headers.cookie || '');
              var setCookieHeaders = Object.keys(cookies).map(function(name) {
                  var value = cookies[name];
                  return libCookie.serialize(name, value, {
                      path: config.prefix + nextUri.protocol + '//' + nextUri.host + '/'
                  });
              });
              data.clientResponse.redirectTo(uri.query.__proxy_cookies_to, {
                  'set-cookie': setCookieHeaders
              });
          }
  
          // todo: copy cookies over from clientRequest when the remote server sends a 3xx redirect to a differnet protocol / subdomain
      }
docs: normally we do nothing here, but when the user is switching protocols or subdomains, the handleResponse function will rewrite the links to start with the old protocol & domain (so that we get sent the cookies), and then it will copy the old cookies to the new path