@Override
    public int compareTo(Mod o) {
        return this.modId.compareTo(o.modId);
    }
@Test
    public void comparable() {
        mod1 = new Mod(AAA);
        mod2 = new Mod(BBB);
        assertNotEquals("what?", mod1, mod2);
        assertTrue(mod1.compareTo(mod2) < 0);
        assertTrue(mod2.compareTo(mod1) > 0);
    }