protected function getContent()
    {
        $this->currentURL = $this->urlEncode($this->currentURL);
        if (!$this->urlValidate($this->currentURL)) {
            throw new SitemapParserException('Invalid URL');
        }
        try {
            if (!isset($this->config['guzzle']['headers']['User-Agent'])) {
                $this->config['guzzle']['headers']['User-Agent'] = $this->userAgent;
            }
            $client = new GuzzleHttp\Client();
            $res = $client->request('GET', $this->currentURL, $this->config['guzzle']);
            return $res->getBody();
        } catch (GuzzleHttp\Exception\TransferException $e) {
            throw new SitemapParserException($e->getMessage());
        }
    }