The answer to that would depend on why the script needs to know that. Ie. What will the script do different?

I guess I'm having trouble trying to conceive of why you would make the module a command line argument rather than having it inside the script. I originally thought that you might have two or modules that offer the same interface, but different implementation. This would mean that the rest of the script wouldn't care which of the alternative modules was loaded, it would just use the exported entrypoints from whichever one was loaded.