Unfortunately, Python being hopelessly dynamic, `A.b` could involve executing arbitrary code and side effects depending on what `A` is. So hoisting `A_b = A.b`

Unfortunately, Python being hopelessly dynamic, `A.b` could involve executing arbitrary code and side effects depending on what `A` is. So hoisting `A_b = A.b` out of the loop may produce different results and thus can't be done automatically without some kind-of incredibly (impossibly?) smart static analysis :( (though perhaps a JIT could perform this optimization for the usual, non-surprising path)