Absolutely.

yeah I feel like you got lucky

'm n ttl grmnt wth ths cmmnt!

Can you post an example that is not expected to fail but fails?

OK. Good.

Did you read this part?

If you don't find two consecutive F(m) verifying F(m) * F(m+1) = prod you will return

[F(m), F(m+1), false] or {F(n), F(n+1), 0} or (F(n), F(n+1), False)

Giving a size would not solve the "what happens if the ball just touches the window" at all though.