You have a good point about TDD, and I'm unsure how to address it. However, you might find the itertools library helpful, particularly itertools.permutations()

You have a good point about TDD, and I'm unsure how to address it. However, you might find the itertools library helpful, particularly itertools.permutations(): http://docs.python.org/library/itertools.html#itertools.permutations http://docs.python.org/library/itertools.html#itertools.perm...