def chunks(total, step):
    assert total >= step
    while total > step:
        yield step;
        total -= step;
    if total:
        yield total

>>> chunks(12, 4)
[4, 4, 4]
>>> chunks(13, 4)
[4, 4, 4, 1]


I'm not sure how appropriate "chunks" is as a name for such a function.

Now I wonder, would it make sense to have something like this into
itertools module?