[Python] Rolling or sliding window iterator?

I need a rolling window (aka sliding window) iterable over a sequence/iterator/generator. (Default Python iteration could be considered a special case, where the window length is 1.) I'm currently using the following code. How can I do it more elegantly and/or efficiently?

def rolling_window(seq, window_size):
it = iter(seq)
win = [it.next() for cnt in xrange(window_size)] # First window
yield win
for e in it: # Subsequent windows
win[:-1] = win[1:]
win[-1] = e
yield win

if __name__=="__main__":
for w in rolling_window(xrange(6), 3):
print w

"""Example output:
[0, 1, 2]
[1, 2, 3]
[2, 3, 4]
[3, 4, 5]
"""


For the specific case of window_size == 2 (i.e., iterating over adjacent, overlapping pairs in a sequence), see also How can I iterate over overlapping (current, next) pairs of values from a list?.

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