Python challenges or projects with just the standard library?

I've been slowly learning python for some months already. I used the Python Crash Course book from No Starch Press, it teaches the basics and then goes on with some projects with pygame, matplotlib, etc.

However, I feel that my Python skills aren't very good yet, and before learning to use libraries I would like to have a better command of the standard library.

I have been looking for some book with projects or, even better, challenges using just the standard library, but haven't found any good ones. Most of them either are for absolute beginners, or use additional libraries, or are very technical and without focus on practice.

Do you know of any good book or resource with challenges or projects that don't depend on additional libraries? Or, do you have any idea for a project or challenge using just the standard library?

Thanks in advance!