An intern had trouble with an outdated exercise in Elixir that use an old version of an Erlang dependency, so we got to figure out how to depend on a local copy, dig into the Erlang code and do a little hack to make it work.

Basically it relied on a checksum algorithm that was previously in yet another external library but was now in the standard library so that call needed to be updated and variables carrying around the old external library had to be underscored out.

It was a good lesson in traversing error messages and going from an angry VM step by step to a clean success. Not to hairy for a junior to understand when explained, and also not too time consuming to burn out interest, while still a bit of a challenge.