catch-all. When `command = "shutdown"` (which isn't in any case), the variable `result` never gets set, and line 11 crashes with a `NameError`. Add a `case _:` block at the end so unmatched commands ...

Claude generated a grade-letter chain. The output for `score = 95` is `B` body: "The first true branch wins. The `A` check has to come *before* the `B` check, or 95 falls into B." - level: 2 body: ...