The `(&values).into_iter()` construct used in the solution to the
iterators exercise is kind of awkward and always gets questions from
students. I think the better thing would be to use the `iter` method to
get the initial iterator, as that's the more idiomatic way to. It's also
an opportunity to point out that there are helper methods for getting an
iterator for a collection.
The files in this directory make up the content of the course. The files here
can include third-party content from ../third_party/ as well.
When we publish a translation of the course, we git restore the src/ and
third_party/ directories at the repository root back to the date listed in the
POT-Creation-Date header of the translation. It is crucial, that all
translatable content lives in those two directories. The other files (such as
book.toml and theme/) are not restored and we always use the latest version
of them.