private boolean IsKilled(Statement s,Statement ifKilled) {
         switch (s.baseOperation) {
            case BINATY_OPERATION:
                BinaryOperationStatement bin = (BinaryOperationStatement)s;
                return helpIsKilled(bin.lhv, ifKilled);
            case UNARY_OPERATION:
                UnaryOperationStatement u = (UnaryOperationStatement)s;
                return helpIsKilled(u.lhv, ifKilled);
            case ASSIGN:
                AssignmentStatement as = (AssignmentStatement)s;
                return helpIsKilled(as.lhv, ifKilled);
            default:
        }
        return false;
    }