sel 0 cons X sel s cons sel X Z dbl 0 0 dbl s s dbls nil nil dbls cons cons indx nil nil indx cons cons from cons sel 2 0 0 cons 0 s 0 dbl 1 dbls 1 nil 0 indx 1 from 0 FULL ./TRS/TRCSR/Ex3_2_Luc97_L.trs