Just wondering if there's a better way to check for equality here. Isn't it possible that in a photograph of 4 people, the first 3 faces are detected in the first pass, and in the second pass, the last 3 faces are detected. In that case, they wouldn't be the same 3. Do the `face` objects contain any sort of unique identifier? (e.g. in the same manner that `touch` events do)