A function that is supposed to compute something should not print something as well. Imagine you want to use this function somewhere else (e.g. in a loop). Your screen would be flooded

You should number indices from 0 to n-1, so can use modulo smoothly.

Note that the instruction pointer wraps around the screen!

What exactly does that mean? Let's say may row has a width of 10 and I want to access the element at x=11. Do I access x=11%10=1 instead? Or x=0 but in the next row?

Did you figure it out?

Cheating! :-P

Interesting to inherit from set. However, this way a function can only be added once. This is probably the wanted behaviour, but not clear from the problem description.