[WIP] More docs and tests

[espottesmith]

Description

PR #6 added a significant body of tests but notably left transforms.jl untested. This PR will fill that gap and (hopefully) significantly improve test coverage.

Dependency and version changes

N/A

Change features

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Refactor (change, which could be breaking or non-breaking, that mainly involves reorganizing code)
• This change requires a documentation update
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Other (please describe below)

Add tests

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have added tests that prove my fix is effective or that my feature works
• I have run tests locally, and all tests passed
• My changes generate no (new) warnings

[codecov-commenter]

Codecov Report

❌ Patch coverage is 94.31818% with 5 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.19%. Comparing base (500d75f) to head (aa9d04a).
⚠️ Report is 4 commits behind head on main.

Files with missing lines	Patch %	Lines
src/core/transform.jl	94.31%	5 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main      #11       +/-   ##
===========================================
+ Coverage   62.58%   92.19%   +29.61%     
===========================================
  Files           8        8               
  Lines        1983     1960       -23     
===========================================
+ Hits         1241     1807      +566     
+ Misses        742      153      -589     

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