public static function setAutoSize($colAlphaStart=NULL, $colAlphaEnd=NULL, $value=true)
    {
        $sheetObj = self::validSheetObj();

        $colStart = ($colAlphaStart) ? self::alpha2num($colAlphaStart) : self::$_offsetCol + 1;
        $colEnd = ($colAlphaEnd) 
            ? self::alpha2num($colAlphaEnd) 
            : self::alpha2num($sheetObj->getHighestColumn());

        foreach (range($colStart,$colEnd ) as $key => $colNum) {
            $sheetObj->getColumnDimension(self::num2alpha($colNum))->setAutoSize($value);
        }

        return new static();
    }