return apply0((BuDDyBDD) that, opr);
BuDDyBDD c = (BuDDyBDD) that; int b = apply0(_id, c._id, opr.id); return new BuDDyBDD(b);
        public BDD apply(BDD that, BDDFactory.BDDOp opr) {            return apply0((BuDDyBDD) that, opr);        }