CoFixpoint imemo_make (fn:A) : Stream A :=
  let fn1 := g fn in
  Cons fn1 (imemo_make fn1).Definition imemo_list := let f0 := f 0 in
  Cons f0 (imemo_make f0).

(* Specifications: *)
Theorem imemo_get_correct: forall n, memo_get n imemo_list = f n.