In the section "Using the batteries" of the "Idioms and Anti-Idioms in
Python" document
(http://docs.python.org/dev/howto/doanddont.html#using-the-batteries),
the reduce statement is used for summing up numbers as an example. I
think this is rather an anti-example, because Python already has a sum
function built-in, i.e. reduce(operator.add, nums)/len(nums) can be
written much simpler as sum(nums)/len(nums).