@Override
   public boolean removeIf(IntPredicate filter) {
      throw new UnsupportedOperationException("RangeSet is immutable");
   }
@Test(expected = UnsupportedOperationException.class)
   public void removeIfObject() {
      RangeSet rs = new RangeSet(4);
      rs.removeIf((Integer i) -> i == 3);
   }