static <A> Set<S> lookupAllAsCISet(Map<A, S> map, Collection<A> l) {
  Set<S> out = ciSet();
  if (l != null) for (A a : l)
    addIfNotNull(out, map.get(a));
  ret out; 
}

static <A> Set<S> lookupAllAsCISet(Collection<A> l, Map<A, S> map) {
  ret lookupAllAsCISet(map, l);
}