(** ** Singleton *)

(* Specifications: *)
Lemma singleton_rb x : Rbt (singleton x).
(** ** [makeBlack] and [makeRed] *)
Lemma makeBlack_rb n t : arbt n t -> Rbt (makeBlack t).
Lemma makeRed_rr t n :
rbt (S n) t -> notred t -> rrt n (makeRed t).