From charlesreid1

Talk on YouTube from RailsConf KC 2016:

This uses the idea of a nursery rhyme to teach refactorization of code. This is actually language-specific:

Equivalent to how going through CSE 142 and CSE 143 material and exercises for a language is great practice.

Well, yes, but it's not a matter of whether it's useful - it's a matter of time and progress.