It's not hard to roll your own (which I know many have done). eg: <https://github.com/bobgeis/aoc2021/blob/32ad206fd5686caec22b707beaf101a1c258206c/lib/shenanigans.nim#L87>
<https://github.com/technicallyagd/unpack/blob/1b6d749473bfb6bd7b749abf823503df633ba04c/src/unpack.nim#L206>