public function htmlXssClean()
    {
        static $antiXss = null;

        if ($antiXss === null)
        {
            if (class_exists('\\voku\\helper\\AntiXSS'))
            {
                $antiXss = new \voku\helper\AntiXSS();
            }
            else
            {
                throw new \RuntimeException
                (
                    "This method requires \voku\helper\AntiXSS. ".
                    "Install with: composer require voku/anti-xss"
                );
            }
        }

        return $this->newSelf($antiXss->xss_clean($this->scalarString));
    }