public void replaceWith(BDDPairing pair) {
public BDD replaceWith(BDDPairing pair) {
        public void replaceWith(BDDPairing pair) {            BDDPairing c1 = ((TestBDDPairing)pair).b1;            BDDPairing c2 = ((TestBDDPairing)pair).b2;            b1.replaceWith(c1);            b2.replaceWith(c2);            assertSame(b1, b2, "replaceWith");        }