def METHOD_NAME(self):
    for n, k, res in [
            (0, 0, ['']),
            (1, 0, ['0']),
            (1, 1, ['1']),
            (2, 0, ['00']),
            (2, 1, ['01', '10']),
            (3, 2, ['011', '101', '110']),
            ]:
        self.assertEqual(list(all_perm(n, k, 'big')),
                         [bitarray(s) for s in res])