This is a simple package with not a lot of functionality, but if you find anything else that can be useful, or think of a way to rewrite the functions in a more readable or performant way while keeping the test passing, I would love to see a pull request! I would be immensely grateful.
As you might've notice, all of the source code is intentionally written in ES5. This is to make the code as backwards compatible as possible without having to add any transpilation step to the build process. In fact, as it is, there's no build process at all.