static <A, B> Collection<B> values(Map<A, B> map) {
  ret map == null ? emptyList() : map.values();
}

ifclass MultiMap
static <A, B> Collection<B> values(MultiMap<A, B> mm) {
  ret mm == null ? emptyList() : concatLists(values(mm.data));
}
endif

ifclass SmallestListMultiMap
static <A, B> Collection<B> values(SmallestListMultiMap<A, B> mm) {
  ret mm == null ? emptyList() : concatLists(values(mm.asMap()));
}
endif