Three Dollar Quill

I've updated the base node classes for the System F implementation, thereby breaking everything else. I should just need to keep iterating on this until I fix all of the Mypy errors, but I'm not going to do that right now, since it's late and my focus is going elsewhere.

So, I'm not going to do any of this tonight, but here's what I think needs to happen:

• Get the code to pass Mypy.
• Get the tests to pass Mypy.
• Get the tests to pass.
• Take a break.
• Audit the code organization; there is a lot of "this technically works, which is good enough for now".
• Address test coverage gaps.
• Fix the many outstanding lints.
• Take another look at the documentation and try to make it nicer.

For now, I'm going to wind down and doodle.

Good night.