Use random.shuffle
:
>>> import random
>>> l = [1,2,3,4]
>>> random.shuffle(l)
>>> l
[3, 2, 4, 1]
random.shuffle(x[, random])
Shuffle the sequence x in place. The optional argument random is a
0-argument function returning a random float in [0.0, 1.0); by
default, this is the function random().