Count by listing, count by multiplying

You will count signals made from coloured flags in two ways: by listing them all with itertools.product, and by the multiplication principle. The checker tells you whether the two ways agree.

The idea. product(colours, repeat=2) gives every pair of colours, repeats included. A signal needs two different flags, so keep only the pairs whose two colours differ.

Your tasks.

1. Set listed to the number of pairs from product(colours, repeat=2) with two different colours.
2. Set multiplied to the same count by the multiplication principle, using len(colours).
3. Set pins to the number of $4$-digit PINs with no digit used twice, by multiplying.