from X cons X n__from n__s X length n__nil 0 length n__cons X Y s length1 activate Y length1 X length activate X from X n__from X s X n__s X nil n__nil cons X1 X2 n__cons X1 X2 activate n__from X from activate X activate n__s X s activate X activate n__nil nil activate n__cons X1 X2 cons activate X1 X2 activate X X 2.2 activate n__from X activate X activate n__s X s activate X length1 X activate X length n__cons X Y length1 activate Y from X cons X n__from n__s X length1 X length activate X activate n__s X activate X length n__cons X Y activate Y activate n__cons X1 X2 activate X1 activate n__nil nil activate n__from X from activate X length n__cons X Y s length1 activate Y activate n__cons X1 X2 cons activate X1 X2 true length1 X length activate X length n__cons X Y length1 activate Y true Failed! NaTT certifiable-1.6