app app append nil ys ys app app append app app cons x xs ys app app cons x app app append xs ys app app flatwith f app leaf x app app cons app f x nil app app flatwith f app node xs app app flatwithsub f xs app app flatwithsub f nil nil app app flatwithsub f app app cons x xs app app append app app flatwith f x app app flatwithsub f xs 2.2 app app append app app cons x xs ys app app append xs ys app app flatwithsub f app app cons x xs app app flatwith f x app app flatwith f app node xs app flatwithsub f app app flatwith f app leaf x app app cons app f x nil app app flatwith f app leaf x app f x app app flatwith f app node xs app app flatwithsub f xs app app flatwithsub f app app cons x xs app flatwith f app app flatwith f app leaf x app cons app f x app app flatwithsub f app app cons x xs app append app app flatwith f x app app append app app cons x xs ys app append xs app app append app app cons x xs ys app app cons x app app append xs ys app app flatwithsub f app app cons x xs app app flatwithsub f xs app app flatwithsub f app app cons x xs app app append app app flatwith f x app app flatwithsub f xs true app app flatwith f app node xs app app flatwithsub f xs app app flatwithsub f app app cons x xs app app flatwithsub f xs app app flatwith f app leaf x app f x app app flatwithsub f app app cons x xs app app flatwith f x true flatwithsub 0 54152 flatwith 0 1 append 0 1 nil 0 2 app 2 2 0 cons 0 14681 leaf 0 1 node 0 42207 app 2 1 2 11943 app app flatwith f app leaf x app app cons app f x nil false app app flatwithsub f app app cons x xs app app append app app flatwith f x app app flatwithsub f xs false app app flatwith f app node xs app flatwithsub f false app app flatwithsub f app app cons x xs app append app app flatwith f x false app app flatwith f app leaf x app cons app f x false app app flatwithsub f app app cons x xs app flatwith f false app app append app app cons x xs ys app app append xs ys true Failed! NaTT certifiable-1.6