Definition HORec {A} `{ag: ageable A}  {X: Type} (f:  (X-> pred A) -> (X -> pred A)) (x: X) : pred A :=
     mkPred (fun a : A => app_pred (@HORec' A ag X f (level a) x) a).

Lemma cont_HOcont : @HOcontractive A ag unit (fun x _ => f (x tt)).