November 2017
Intermediate to advanced
670 pages
17h 35m
English
Looking at the last line of output, we can see that we have called our Reduce function to sum our totals (totalQuantity, totalPrice, and totalListPrice):

For a quick manual verification, let's look at totalQuantity--1+2+5+1+2+5+1+2+5 = 24. Looks good!