Isra/optional default

[isra17]

I was investigating why Optional default was broken (ie. x: Optional[int] = 1 would default to None) and ended up refactoring a good bunch of the code, finding out that defaults seemed to be overall quite broken.

[codecov[bot]]

Codecov Report

Merging #269 (3e9b593) into main (0c43ff5) will not change coverage. The diff coverage is 100.00%.

@@            Coverage Diff            @@
##              main      #269   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            6         6           
  Lines          472       476    +4     
  Branches        90        93    +3     
=========================================
+ Hits           472       476    +4     

Impacted Files	Coverage Δ
src/desert/_make.py	100.00% <100.00%> (ø)
tests/test_make.py	100.00% <100.00%> (ø)

[desert-bot]

FYI I don't personally have time to work on this repo these days. Other collaborators should be able to review if they're interested, so you might ping someone to see if there's interest.