Changing exercise with enumerate() to a simpler example.

[lwrubel]

Addresses issue #378: "02-loop example should not suggest naive evaluation of polynomials".

[maxim-belkin]

Thanks, Laura. I like your changes (with a minor note that I'm not sure about using start=1 the first time enumerate is used... that is probably fine...).

Your exercise also highlights the importance of talking about lists first. There is a lists-loops branch that does that but I haven't had a chance to look into that switch more closely (need to verify that the logic of episodes does not break somewhere).

[lwrubel]

Thanks, yes, I think this would require that lists come before loops in the curriculum, should have caught that. FWIW, I totally support having lists before loops, because it makes it possible to have relevant and realistic exercises and challenges with loops.

[maxim-belkin]

I've added status:wait label to indicate that this issue depends on having episode on lists before the episode on for loops