public override void Eval(Executor exec)
{
Function fResultRelation = exec.PopFxn();
Function fArgRelation = exec.PopFxn();
Function fBaseCase = exec.PopFxn();
Function fCondition = exec.PopFxn();
BinRecHelper h = new BinRecHelper(exec, fResultRelation, fArgRelation, fBaseCase, fCondition);
h.Exec();
}