private function writeCellSpan(XMLWriter $objWriter, $curColumn, $prevColumn)
    {
        $diff = $curColumn - $prevColumn - 1;
        if (1 === $diff) {
            $objWriter->writeElement('table:table-cell');
        } elseif ($diff > 1) {
            $objWriter->startElement('table:table-cell');
            $objWriter->writeAttribute('table:number-columns-repeated', $diff);
            $objWriter->endElement();
        }
    }