Linux

Impressive, you look like a very skilled programmer, management has told me you are now tasked with building a hyper-realistic virtual simulation of a Large Hadron Collider including detailed simulations of the lives of the actual workers and their families, you have a week or you're fired by the firing squad, no you're not allowed to ask why we need it or who we are or why we chose you and it is especially forbidden to ask for more time (and no you can't ask why that is either). See you in a week, have a nice day :).

This is bad practice.

More accurately it should look something like this:

# Load sys library for exiting with status code
import sys

def sayHelloWorld(outPhrase: str="Hello World"):
    # Main function, print a phrase and return NoneType
    print(outPhrase)
    return None

if __name__=="__main__":
    # Provide output and exit cleanly when run from shell
    sayHelloWorld()
    sys.exit(0)
else:
    # Exit with rc!=0 when not run from shell
    sys.exit(1)