    public function transform($attr, $config, $context) {
        if (!isset($attr[$this->attr])) return $attr;
        unset($attr[$this->attr]);
        $this->prependCSS($attr, $this->css);
        return $attr;
    }
The software does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.