[KorvinSzanto]

I would rewrite these functions for fun, even with an understanding of them. It doesn't matter if the end result is useful or not, we're programmers, we enjoy programming, not using. Of course that's to a point; time spent making something useful that's fun to make is more rewarding to most.

I'm just making the point that it's not just about learning, it's about writing the code. If you're the type of programmer that is only looking for a means to an end, this isn't for you, but if you're like me, the fun is in figuring it out yourself without the help of libraries.