Sync code snippets with version in code repo

I made some small changes to the code when moving it into the separate code repo. The code snippets in the course materials should be updated to be in sync with this repo.

NB: I plan on making some more small changes to the code, so it might be worth holding off on this issue for now.

Compare the code snippets in the course materials with the separate code repository, starting by identifying which snippets differ from the repository. Wait for the planned code changes before beginning; done means the course snippets match the final repository version.

Written by the indexing model from the issue text.