Well, I got calling functions from outside working, and getting the tests to pass wasn't too bad. I went a bit further. Implementing tags wasn't too much of a hassle. Now, I have to handle lists, finally, which I suspect might end up being nearly as much of a hassle as the original few tests were, where there was practically nothing implemented.
Here's what needs to happen, more or less... There are a bunch of support classes just for working with Ink lists, and I need to follow each one from creation until I'm sure it's done mutating. Given that some of these classes have members called "cache" on them, that might technically not happen.
But, when the time comes (tomorrow), I'll get to work on it and see what I can get out of the source code.