I'm left with a good impression. Lot's of comments on the whys and historic context. Backed by tons of tests. Yes the file could use some modularisation and

I'm left with a good impression. Lot's of comments on the whys and historic context. Backed by tons of tests. Yes the file could use some modularisation and splitting into smaller parts but maybe the gains were weighted and judged against. That file is a great example of KISS.