(** * The list of integers between 1 and n (inclusive) *)
Fixpoint until (n : nat) : Zlist :=
match n with
| O => Nil Z
| S n => Cons Z (Z_of_nat (S n)) (until n)
end.

Lemma until_pos : forall (n : nat) (x : Z), inlist Z x (until n) -> (0 < x)%Z.