from functools import reduce

my_list = [1,2,3]

def accumalator(acc, item):
    print(acc, item)
    return acc + item

print(reduce(accumalator, my_list, 10))

# What reduce does?

# reduce take the function given and take item from the
# iterable and pass to function given to it. The first
# parameter is the value initialized as the 3rd argument
# to the reduce function. It do the processing and returns
# a value which is used as next initialiizing value for the
# first argument of the function provided in the reduce function
# and so on for all items in iterable.