@Override
   public boolean containsAll(Collection<?> c) {
      if (c instanceof IntSet) {
         return containsAll((IntSet) c);
      }
      for (Object o : c) {
         if (!contains(o))
            return false;
      }
      return true;
   }
@Test
   public void containsAll() throws Exception {
      RangeSet rs = new RangeSet(4);
      RangeSet rs2 = new RangeSet(4);

      assertTrue(rs.containsAll(rs2));

      RangeSet rs3 = new RangeSet(3);

      assertTrue(rs.containsAll(rs3));
      assertFalse(rs3.containsAll(rs));
   }