public function parseXml($xmlString)
    {
        Validate::notNull($xmlString, 'xmlString');
        Validate::isString($xmlString, 'xmlString');
        $categoryXml = simplexml_load_string($xmlString);
        $attributes = $categoryXml->attributes();
        if (!empty($attributes['term'])) {
            $this->term = (string) $attributes['term'];
        }

        if (!empty($attributes['scheme'])) {
            $this->scheme = (string) $attributes['scheme'];
        }

        if (!empty($attributes['label'])) {
            $this->label = (string) $attributes['label'];
        }

        $this->undefinedContent = (string) $categoryXml;
    }