static <A> ItIt<A> strategyIterator(Best<A> best, Steppable strategy, O... _) {
  optPar Double optimumValue;
  ret iff(func {
    if (optimumValue != null && eq(best.score(), optimumValue)) ret endMarker();
    A lastBest = best!;
    if (strategy.step()) ret endMarker();
    ret best! == lastBest ? null : best!;
  });
}