Reduce function with three parameters

Question

How does reduce function work in python3 with three parameters instead of two. So, for two,

tup = (1,2,3)
reduce(lambda x, y: x+y, tup)
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Answer 1

Providing a tuple as a third parametr we will be able to calculate and return from reduce multiple values.

from functools import reduce
def mean(my_list):                  # == sum(my_list) / len(my_list)
    return (lambda x: x[0]/x[1]) (reduce(lambda x, y : (x[0]+y, x[1]+1), 
                                                my_list, (0, 0,)))