x,y = y,x range(6, 0, -1)

>>> range(6, 0, -1)
[6, 5, 4, 3, 2, 1]
>>> range(0, 5)
[0, 1, 2, 3, 4]
>>> range(0, 5,3)
[0, 3]
>>> x=2
>>> y=3
>>> x,y
(2, 3)
>>> x,y = y,x
>>> x,y
(3, 2)
>>>