// returns optimized specimen, score
static <A> Pair<A, Double> racerOptimize(RandomAndVary<A> r, F1<A, Double> scorer, O... _) {
  new AIStrategy_Racer_RandomWithVary<A> strategy;
  strategy.submit = scorer;
  strategy.random = func -> A { r.randomInstance() };
  strategy.vary = func(A a) -> A { r.varyInstance(a) };
  ret bestAsPair(runStrategyWhileImprovement(strategy, _));
}