As a followup to my earlier post, this is an even better way to do it, IMNSHO.
Don't use $ARG or $_ at all. Assign to a variable that explicitly names the variable you expect.
Because the Pythonic way is: Explicit is better than implicit.
Let me just say now that if you don't like the Pythonic way, that's cool. I'm not here to beat you over the head with it. So please give me the same respect I give you and just move along if you don't find this blog to your liking. If mocking other people is more to your liking, go do it somewhere else.