I agonised over this. I did originally have a version that used 2-element arrays instead, but the resulting code felt more dense and hard to follow. I figured

I agonised over this. I did originally have a version that used 2-element arrays instead, but the resulting code felt more dense and hard to follow. I figured that people who know enough to point this out already know what's up. People who don't will benefit from the code being easier to read.