The very first "refactor" is broken, the last line should be `make_pizza(["ham", "pineapple"])`. Which is actually very easy to notice if you actively watch out

The very first "refactor" is broken, the last line should be `make_pizza(["ham", "pineapple"])`. Which is actually very easy to notice if you actively watch out for repetitions. Ironically the author just demonstrated why DRY is a great principle.