Hot take on Modal (@wryl, @neauoire): Just use sed scripts lol

Attached in the screenshot of my addition program in action.

The process is:
- Take two numbers as two number lines.
- Turn each into Roman-ish numerals.
- Turn into unary.
- Concatenate.
- Turn back into Arabic, for now as a sum.
All done with global POSIX regex substitution, of course.