Find the Last Empty Locker

New kid at school gets their pick of the empty lockers — and wants the one farthest down the hall. 🔒

You get a list where each locker is empty or full. Print the position (from 0) of the LAST empty locker, or none if the hall is packed.

Example:

Input: lockers = ["full", "empty", "full", "empty", "full"] Output: 3

Empty lockers sit at positions 1 and 3. Overwriting the saved position every time you pass one leaves 3 — the last one.