(* Lemma Znth_map' : forall {A B} i (f : A -> B) al b, Znth i (map f al) (f b) = f (Znth i al b). *)

(* Specifications: *)
Lemma Znth_upto : forall d m n,
0 <= n < Z.of_nat m -> @Znth _ d n (upto m) = n.