Except the python3 str change was pretty big (and centered again, on those things that aren't just strings in POSIX). Getting the correct `bytes` that went in

Except the python3 str change was pretty big (and centered again, on those things that aren't just strings in POSIX). Getting the correct `bytes` that went in your program uses completly different interfaces compared normal python use , for example, you now need to use `os.environb` instead of `os.environ` if you want to use arbitrary POSIX-compliant `bytes` environment variables and `argvb = [os.fsencode(a) for a in sys.argv]` instead of just `argv` for POSIX-compliant `bytes` command line arguments. As people suggest in https://peps.python.org/pep-0383/ https://peps.python.org/pep-0383/ , handling really arbitrary inputs is tough work.