It renders correctly on Manyverse but it doesn't on Patchwork.

Let me paste the extra content below:

I've implemented them using some more advanced Racket stuff that I'm learning about.

For example both functions are declared with contracts. They make sure you can only call them passing the correct value types.

I've also implemented test and a main submodules. This means that the test submodule always run before main thus making sure the library works before trying to execute. The main submodule runs if you're not importing the library but running it as the main script.