protected function startDocument()
    {
        $xml = $this->getXml();
        $xml->startDocument('1.0', 'UTF-8');
        $xml->startElement('tweakwise'); // Start root
        $xml->writeElement('shop', $this->storeManager->getDefaultStoreView()->getName());
        $xml->writeElement('timestamp', $this->getNow()->format('Y-m-d\TH:i:s.uP'));
        $this->flush();
        return $this;
    }