protected function extractStyleAttributes($xmlReader)
    {
        while ($xmlReader->read()) {
            if ($xmlReader->isPositionedOnStartingNode(self::XML_NODE_XF)) {
                $numFmtId = $xmlReader->getAttribute(self::XML_ATTRIBUTE_NUM_FMT_ID);
                $normalizedNumFmtId = ($numFmtId !== null) ? intval($numFmtId) : null;

                $applyNumberFormat = $xmlReader->getAttribute(self::XML_ATTRIBUTE_APPLY_NUMBER_FORMAT);
                $normalizedApplyNumberFormat = ($applyNumberFormat !== null) ? !!$applyNumberFormat : null;

                $this->stylesAttributes[] = [
                    self::XML_ATTRIBUTE_NUM_FMT_ID => $normalizedNumFmtId,
                    self::XML_ATTRIBUTE_APPLY_NUMBER_FORMAT => $normalizedApplyNumberFormat,
                ];
            } else if ($xmlReader->isPositionedOnEndingNode(self::XML_NODE_CELL_XFS)) {
                // Once done reading "cellXfs" node's children
                break;
            }
        }
    }