[nutate]

Let's say you wanted to run some python code that was written and test it against some C/C++/Rust for accuracy of some sort (numerical, lexicographical, etc). In the old way you would have to fire up multiple processes to do that (like OS level processes) but now you can have your multithreaded compiled code running in threads and your multi-GIL'd interpreted code running all in one process and comparing their results in the `main` of your C/C++/Rust. That's a contrived example, but the issue was that a single GIL isn't threadsafe in and of itself. So if you're using these compiled languages as sort of python runners you couldn't multithread python interpreter execution and guarantee the code working. Also as the above comment stated, you could do hacks, but you'd double your memory allocation by needing a python and C/C++/Rust representation for everything that went back and forth.