That's what I did the other day when I only needed one function. That is, I removed each arg when using it and then if there's anything left it's an error. I wished for the Perl6 // operator, but by checking for an undef value rather than definedness in the hash, I only mentioned the actual key once and so didn't bother making it a helper function.
I think I'll use your function (or one like it) next time I want simple argument naming. Thanks.