public ImmutableBooleanSet newWithAll(BooleanIterable elements) {
   ImmutableBooleanSet result = this;
   BooleanIterator booleanIterator = elements.booleanIterator();
   while (booleanIterator.hasNext()) {
     result = result.newWith(booleanIterator.next());
   }
   return result;
 }
 public boolean containsAll(BooleanIterable source) {
   BooleanIterator iterator = source.booleanIterator();
   return !iterator.hasNext();
 }