public void applyWith(BDD that, BDDOp opr) {
public BDD applyWith(BDD that, BDDOp opr) {
        public void applyWith(BDD that, BDDOp opr) {            BDD c1 = ((TestBDD)that).b1;            BDD c2 = ((TestBDD)that).b2;            b1.applyWith(c1, opr);            b2.applyWith(c2, opr);            assertSame(b1, b2, "applyWith "+opr);        }