The idea is pretty simple. Nearly all command line Python programs use argparse to simplify picking options and arguments off the command line as well as providing some help. The Gooey decorator ...

With a command-line switch ... To select a specific installation of Python, just pass the version as the first element in the argument list. Any arguments provided after the version are passed ...

Others might reasonably choose, say, Python or Go instead, and I wouldn't judge. The real point is that we're focusing on the command line itself. Everything below is something you can easily ...