Zip Keyword in For loop

[ichabod801]

Maybe a clearer example would help. Say you have a = [1, 2, 3] and b = [6, 5, 4]. Then list(zip(a, b)) would be [(1, 6), (2, 5), (3, 4)]. The zip function returns a tuple of the first item in each list passed to it, then a tuple of the second item in each list, then a tuple of the third item, and so on until one of the lists runs out of items. Using for e, f in the loop is tuple assignment, assigning each item in the tuples returned by zip to the respective variables on the left.

That makes dot in your example equal to 1 * 2 + 2 * 1.