@Override
   public boolean containsAll(IntSet set) {
      int size = set.size();
      return size == 0 || size == 1 && set.contains(value);
   }
@Test
   public void testContainsAll() throws Exception {
      IntSet sis = new SingletonIntSet(3);
      IntSet sis2 = new SingletonIntSet(3);

      assertTrue(sis.containsAll(sis2));
      assertTrue(sis2.containsAll(sis));

      IntSet sis3 = new RangeSet(4);

      assertTrue(sis3.containsAll(sis));
      assertFalse(sis.containsAll(sis3));
   }