/**
  * Retrieve the return URL from the cookie
  * 
  * @return string
  */
 public static function getReturnURL()
 {
     $cookieName = self::COOKIE_PREFIX . self::COOKIE_RETURNURL;
     $returnURL = self::_getCookieData($cookieName);
     self::_clearCookieData($cookieName);
     if (empty($returnURL)) {
         $returnURL = Rublon_Transients::getTransient('rublon_login_redirect');
     }
     return !empty($returnURL) ? $returnURL : '';
 }