This seems like a bad idea, when a regular Role can do the same thing
(functioning as an Interface) and totally avoid MI.
Not to mention 'requires' is a kinda shitty subset of the functionality
needed to make a good interface. Roles add "exlclude" but even this
isn't really enough.. What if I want to make my Interface dependent on a
method modifier, global variable, or some other internal nicety -- there
is no convenient nicety that can do this..