2nd cons X head XS sel s N cons X sel N XS from X cons X head cons X X take 0 XS nil take s N cons X cons X sel 0 cons X X 2nd 1 cons 1 head 1 sel 2 s 1 from 1 take 2 0 0 nil 0 FULL ./TRS/TRCSR/Ex7_BLR02_L.trs