public static function getUnits() {
        return [
            self::FILE_SIZE_UNIT_B,
            self::FILE_SIZE_UNIT_KB,
            self::FILE_SIZE_UNIT_MB,
            self::FILE_SIZE_UNIT_GB,
            self::FILE_SIZE_UNIT_TB,
            self::FILE_SIZE_UNIT_PB,
            self::FILE_SIZE_UNIT_EB,
            self::FILE_SIZE_UNIT_ZB,
            self::FILE_SIZE_UNIT_YB,
        ];
    }