return value / 10 - o.value / 10;
    }

    @Override
    public String toString() {
      return Integer.toString(value);
    }
  }

  public void testCopyOfDuplicateInconsistentWithEquals() {
    IntegerDiv10 three = new IntegerDiv10(3);
    IntegerDiv10 eleven = new IntegerDiv10(11);
    IntegerDiv10 twelve = new IntegerDiv10(12);
    IntegerDiv10 twenty = new IntegerDiv10(20);