Implement `strength(pw)` returning one of six labels based on the five rules. Run on 4 passwords and print each label: "abc" -> weak (1 rule passes — lowercase only) "abcdef12" -> ok (3 rules) "Abcdef12" -> good (4 rules) "Abcdefgh1234!" -> very strong (5 rules) (Score 0 = "very weak" — empty string / nothing passes. None of the 4 test inputs hit that, but the label is still in the table.) Expected: weak ok good very strong