Getting a series of accumulated values based on an iterable is a common requirement. With the help of the itertools.accumulate() function, we don’t need to write any loops to implement.

import itertools

import operator

nums = [1, 2, 3, 4, 5]

print(list(itertools.accumulate(nums, operator.mul)))

# [1, 2, 6, 24, 120]

The above program is the same as follows if we wouldn't like to use the operator.mul:

import itertools

nums = [1, 2, 3, 4, 5]

print(list(itertools.accumulate(nums, lambda a, b: a * b)))

# [1, 2, 6, 24, 120]