docs: function getClientIp(req) {
      var xff = req.get('x-forwarded-for');
      if (xff) {
        var ips = xff.split(',').map(function onIp(ip) {
          return ip.trim();
        });
        var ip = ips[ips.length - 1];
        if (ip) {
          return ip;
        }
      }
      return req.ip;
    }