public static void listTest()
        {
            MyCons <string> ls  = new MyCons <string> ("abc", null);
            MyCons <string> cdr = MyCons <string> .returnCdr(ls);

            if (cdr != null)
            {
                error("cdr is not null");
            }
        }
 public static MyCons <T> returnList(MyCons <T> l)
 {
     return(l);
 }
 public static MyCons <T> returnCdr(MyCons <T> cons)
 {
     return(returnList(cons.cdr));
 }
 public MyCons(T _car, MyCons <T> _cdr)
 {
     //printCar (_car);
     car = _car;
     cdr = _cdr;
 }