Assert.assertTrue(llist.contain(2));
Assert.assertFalse(llist.contain(3));
environment.worldPop();
Assert.assertFalse(llist.contain(1));
Assert.assertFalse(llist.contain(2));
Assert.assertFalse(llist.contain(3));
llist.add(1);
llist.add(2);
Assert.assertTrue(llist.contain(1));