Let us say a package forks. Or there are two packages that provide much similar functionality. I want to say that my package depends on having one or the other of the packages. How would I do that? A concrete example would be: requires nose 0.11.1 or greater OR py.test 1.1.1 or greater (because what I have written is a plugin that works with either, but requires a py.test or a nose that is recent enough to have the plugin architecture) Laura