idiom for initial list of lists

[Robin Becker]

What's the correct way to initialise a list of lists I find that the
natural [[]]*n doesn't work eg
>>> S=[[]]*5
>>> S
[[], [], [], [], []]
>>> S[0].append(1)
>>> S
[[1], [1], [1], [1], [1]]

so I'm forced to use the rather pedantic
S=[]
for i in range(n): S[i].append([])
-- 
Robin Becker