// f : A -> Collection<A>
// trace_out collects what the function returns
// returns hashset including input
static <A> Set<A> transitiveHull(O f, A input, O... _) {
  ret transitiveHullOfFunction(f, input, _);
}

static <A> Set<A> lambdaMapLike transitiveHull(IF1<A, Cl<A>> f, A input, O... _) {
  ret transitiveHullOfFunction(f, input, _);
}