to snake or not to snake

gistfile1.txt

In [42]: x = cycler('x', [1,2,3])

In [43]: y = cycler('y', [1,2])

In [44]: list(bss.snake_cyclers([y, x], [False, True]))
Out[44]: 
[{'x': 1, 'y': 1},
 {'x': 2, 'y': 1},
 {'x': 3, 'y': 1},
 {'x': 3, 'y': 2},
 {'x': 2, 'y': 2},
 {'x': 1, 'y': 2}]

In [45]: list(bss.snake_cyclers([y, x], [False, False]))
Out[45]: 
[{'x': 1, 'y': 1},
 {'x': 2, 'y': 1},
 {'x': 3, 'y': 1},
 {'x': 1, 'y': 2},
 {'x': 2, 'y': 2},
 {'x': 3, 'y': 2}]
 
In [55]: z = cycler('z', [1,2,3])
 
In [56]: list(bss.snake_cyclers([z, y, x], [False, False, False]))
Out[56]: 
[{'x': 1, 'y': 1, 'z': 1},
 {'x': 2, 'y': 1, 'z': 1},
 {'x': 3, 'y': 1, 'z': 1},
 {'x': 1, 'y': 2, 'z': 1},
 {'x': 2, 'y': 2, 'z': 1},
 {'x': 3, 'y': 2, 'z': 1},
 {'x': 1, 'y': 1, 'z': 2},
 {'x': 2, 'y': 1, 'z': 2},
 {'x': 3, 'y': 1, 'z': 2},
 {'x': 1, 'y': 2, 'z': 2},
 {'x': 2, 'y': 2, 'z': 2},
 {'x': 3, 'y': 2, 'z': 2},
 {'x': 1, 'y': 1, 'z': 3},
 {'x': 2, 'y': 1, 'z': 3},
 {'x': 3, 'y': 1, 'z': 3},
 {'x': 1, 'y': 2, 'z': 3},
 {'x': 2, 'y': 2, 'z': 3},
 {'x': 3, 'y': 2, 'z': 3}]
 
In [57]: list(bss.snake_cyclers([z, y, x], [False, True, True]))
Out[57]: 
[{'x': 1, 'y': 1, 'z': 1},
 {'x': 2, 'y': 1, 'z': 1},
 {'x': 3, 'y': 1, 'z': 1},
 {'x': 3, 'y': 2, 'z': 1},
 {'x': 2, 'y': 2, 'z': 1},
 {'x': 1, 'y': 2, 'z': 1},
 {'x': 1, 'y': 2, 'z': 2},
 {'x': 2, 'y': 2, 'z': 2},
 {'x': 3, 'y': 2, 'z': 2},
 {'x': 3, 'y': 1, 'z': 2},
 {'x': 2, 'y': 1, 'z': 2},
 {'x': 1, 'y': 1, 'z': 2},
 {'x': 1, 'y': 1, 'z': 3},
 {'x': 2, 'y': 1, 'z': 3},
 {'x': 3, 'y': 1, 'z': 3},
 {'x': 3, 'y': 2, 'z': 3},
 {'x': 2, 'y': 2, 'z': 3},
 {'x': 1, 'y': 2, 'z': 3}]

 In [58]: list(bss.snake_cyclers([z, y, x], [False, True, False]))
Out[58]: 
[{'x': 1, 'y': 1, 'z': 1},
 {'x': 2, 'y': 1, 'z': 1},
 {'x': 3, 'y': 1, 'z': 1},
 {'x': 1, 'y': 2, 'z': 1},
 {'x': 2, 'y': 2, 'z': 1},
 {'x': 3, 'y': 2, 'z': 1},
 {'x': 1, 'y': 2, 'z': 2},
 {'x': 2, 'y': 2, 'z': 2},
 {'x': 3, 'y': 2, 'z': 2},
 {'x': 1, 'y': 1, 'z': 2},
 {'x': 2, 'y': 1, 'z': 2},
 {'x': 3, 'y': 1, 'z': 2},
 {'x': 1, 'y': 1, 'z': 3},
 {'x': 2, 'y': 1, 'z': 3},
 {'x': 3, 'y': 1, 'z': 3},
 {'x': 1, 'y': 2, 'z': 3},
 {'x': 2, 'y': 2, 'z': 3},
 {'x': 3, 'y': 2, 'z': 3}]