This turned out surprisingly effective, about 2/3s of the tests pass, which is enough for me at the moment. The main missing parts involve a bunch of unsafe things that xz2 doesn't really support (to my knowledge atleast).

As a side note I also abstracted out Compressor like Decompressor was abstracted

Lots of tests are failing because they were previously blocked due to no implementation at all.

Would you be able to squash these commits down? Ideally into one for copying the files from cpython, and one for all the rest?

Sure

It's at 3 now, I committed things in a weird fashion so I can't get it below that.

oh no.. I thought #5728 and this one had shared work of the new compression module

@arihant2math What will be the best way? Is it worth to keep #5728?
if yes, the conflict need to be resolve.
if not, reverting it and merging this can be a way.

Probably easiest to revert, yes.