app app append nil l l app app append app app cons h t l app app cons h app app append t l app app map f nil nil app app map f app app cons h t app app cons app f h app app map f t app app append app app append l1 l2 l3 app app append l1 app app append l2 l3 app app map f app app append l1 l2 app app append app app map f l1 app app map f l2 app 2 append 0 nil 0 cons 0 map 0 FULL ./TRS/higher-order/Lifantsev/Ex3Lists.trs