Allegedly ContT here isn't ContT!

[isovector]

As suggested in the JFP review, my ContT presented here is actually Codensity. I seem to recall being unable to implement callCC, and that's probably why.

[isovector]

This is sorta true; my ContT is actually Codensity Identity, but that distracts from the point I'm trying to make. I think it's probably fine to leave as-is, perhaps with a footnote to explain wtf.