def METHOD_NAME(self):
    a = bitarray('00010011', 'big')
    for s in ['00010101', '00010110', '00011001',
              '00011010', '00011100', '00100011']:
        a = next_perm(a)
        self.assertEqual(a.count(), 3)
        self.assertEqual(a, bitarray(s, 'big'))