def serialized(self):
        to_ret = {}
        for group, requirements in self.items():
            to_ret[group] = [str(requirement) for requirement in requirements]
        return to_ret
def _invert_results(self, candidates):
        inverted_candidates = list(self.directory)

        for candidate in candidates:
            try:
                inverted_candidates.remove(candidate)
            except ValueError:
                pass

        return inverted_candidates