(let ((Y (lambda (f)
           (let ((g (lambda (x)
                      (apply f (list (lambda (z1 z2)
                           (apply (apply x (list x)) (list z1 z2))))))))
             (g g))))
      (newappend (lambda (ap)
                   (lambda (x y)
                     (if (null? x)
                         y
                         (cons (first x)
                               (apply ap (list (rest x) y)))))))
      (l (cons 1 (cons 2 (cons 3 null)))))
  (apply (Y newappend) (list l l)))