private static TailCall<Tuple<List<Double>, RNG>> doublesHelper(
int count, RNG rng, List<Double> xs) {
Tuple<Double, RNG> t1 = doubleRnd(rng);
return TailCall.sus(() -> doubles(count - 1, t1._2, xs.cons(t1._1)));
}
private static TailCall<Tuple<List<Integer>, RNG>> ints2Helper(
int count, RNG rng, List<Integer> xs) {
Tuple<Integer, RNG> t1 = rng.nextInt();
return TailCall.sus(() -> ints2(count - 1, t1._2, xs.cons(t1._1)));
}