static <A, B> ProbabilisticList<B> mapToProbabilisticList(Iterable<A> l, IF1<A, WithProbability<B>> f) {
  ret new ProbabilisticList<B>(map(l, f));
}

static <A> ProbabilisticList<A> mapToProbabilisticList(Iterable<A> l, IF1<A, Double> f) {
  ret new ProbabilisticList<A>(map(l, a -> withProbability(f.get(a), a)));
}