private function writeDrawings(XMLWriter $objWriter = null, PhpspreadsheetWorksheet $pSheet = null, $includeCharts = false)
    {
        $chartCount = ($includeCharts) ? $pSheet->getChartCollection()->count() : 0;
        // If sheet contains drawings, add the relationships
        if (($pSheet->getDrawingCollection()->count() > 0) ||
            ($chartCount > 0)) {
            $objWriter->startElement('drawing');
            $objWriter->writeAttribute('r:id', 'rId1');
            $objWriter->endElement();
        }
    }