This is some example code of calling Assembly from Rust and calling Rust from Assembly.
It's a Rust function, which calls a label written in Assembly, which calls a (different) exported Rust function.
There were no good examples on how to do either of those things.
I've tested with Nightly and Stable as of the time of this writing and it works, I kind of need this so if it breaks I'll probably update it. Or you can PR.