static <A, B extends A> void addAll(Collection<A> c, Iterable<B> b) {
  if (c != null && b != null) for (A a : b) c.add(a);
}

static <A, B extends A> bool addAll(Collection<A> c, Collection<B> b) {
  ret c != null && b != null && c.addAll(b);
}

static <A, B extends A> bool addAll(Collection<A> c, B... b) {
  ret c != null && c.addAll(Arrays.asList(b));
}

ifclass Collector
static <A, B extends A> void addAll(Collector<A> c, Iterable<B> b) {
  if (c != null && b != null) for (A a : b) c.add(a);
}
endif

static <A, B> Map<A, B> addAll(Map<A, B> a, Map<? extends A,? extends B> b) {
  if (a != null) a.putAll(b);
  ret a;
}