public function render()
{
// Create XML writer
$objWriter = new XMLWriter(XMLWriter::STORAGE_MEMORY);
// XML header
$objWriter->startDocument('1.0', 'UTF-8', 'yes');
// a:tblStyleLst
$objWriter->startElement('a:tblStyleLst');
$objWriter->writeAttribute('xmlns:a', 'http://schemas.openxmlformats.org/drawingml/2006/main');
$objWriter->writeAttribute('def', '{5C22544A-7EE6-4342-B048-85BDC9FD1C3A}');
$objWriter->endElement();
$this->getZip()->addFromString('ppt/tableStyles.xml', $objWriter->getData());
return $this->getZip();
}