Improve comments to be LLM friendly, improve Spark compatibility

[goodwanghan]

No description provided.

[codecov-commenter]

Codecov Report

All modified lines are covered by tests ✅

Comparison is base (8e1cf90) 100.00% compared to head (2f9f364) 99.95%.
Report is 1 commits behind head on master.

❗ Your organization needs to install the Codecov GitHub app to enable full functionality.

Additional details and impacted files

@@             Coverage Diff             @@
##            master     #511      +/-   ##
===========================================
- Coverage   100.00%   99.95%   -0.05%     
===========================================
  Files          128      128              
  Lines        12064    12090      +26     
===========================================
+ Hits         12064    12084      +20     
- Misses           0        6       +6     

Files	Coverage Δ
fugue/dataframe/api.py	100.00% <ø> (ø)
fugue/dataframe/utils.py	100.00% <100.00%> (ø)
fugue/execution/native_execution_engine.py	100.00% <ø> (ø)
fugue_dask/_io.py	100.00% <100.00%> (ø)
fugue_spark/_utils/convert.py	95.68% <100.00%> (-4.32%)	⬇️
fugue_spark/_utils/io.py	100.00% <100.00%> (ø)
fugue_spark/dataframe.py	100.00% <100.00%> (ø)
fugue_spark/execution_engine.py	100.00% <100.00%> (ø)
fugue_test/builtin_suite.py	100.00% <100.00%> (ø)

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.