    public function transform($attr, $config, $context) {

        if (!isset($attr[$this->attr])) return $attr;

        $value = trim($attr[$this->attr]);
        unset($attr[$this->attr]);

        if (!$this->caseSensitive) $value = strtolower($value);

        if (!isset($this->enumToCSS[$value])) {
            return $attr;
        }

        $this->prependCSS($attr, $this->enumToCSS[$value]);

        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.