Supporting #48in24?

Would it be best to assume that @jonmcalder is going to be too busy to engage much with this?

I'm currently working with Bethany to add approaches to the Python track (only 118 more to go!). I may also be able to do some R versions in parallel, but that is only really worthwhile if they can be PR'd, reviewed and merged before the week when that exercise is featured.

We're off to a bad start with exercises. The R track has `leap` (week of Jan 16) but is missing `reverse-string` (week of Jan 23). We would have to start by adding the Practice Exercise.