Function autobalance_by 

pub fn autobalance_by<S: Clone, E>(
    stage: &S,
    knobs: &[&dyn Knob<S>],
    settings: &BalanceSettings,
    evaluate: impl FnMut(&S, &Tries) -> Result<PlaytestReport, E>,
    should_stop: impl FnMut() -> bool,
) -> Result<Balanced<S>, E>

autobalance’s search, each setting played by evaluate: the report of the stage it is given, played as the Tries it is given say, its checks judged (a caller with threads plays the seeds on them and playtest::judges them once). Its first error stops the search.

Before each run of the search, should_stop is asked whether to stop (a caller’s clock: the core reads none). Once it says so, the search stops (Stop::Stopped) with the best setting seen, kept back one evaluation as for Stop::Budget: the stage as authored and the setting it ends on are always played at settings.tries, so a search told to stop at once makes the one run of the stage as authored.

Given the same reports from evaluate and the same answers from should_stop, it makes the same runs in the same order and finds the same changes.