static <A> Pair<A, Double> racerOptimize(RandomAndVary<A> r, IF<A, Double> scorer) {
  new AIStrategy_Racer_RandomWithVary<A> strategy;
  strategy.random = func -> A { r.randomInstance() };
  strategy.vary = func(A a) -> A { r.varyInstance(a) };
  ret bestAsPair(runStrategyWhileImprovement(strategy));
}