Canonical Structure unit_ordType := Eval hnf in OrdType unit unit_ordMixin.

(* Specifications: *)
Lemma path_last (A : ordType) (s : seq A) x : path oleq x s -> oleq x (last x s).
Lemma sorted_last_key_max (A : ordType) (s : seq A) x y : sorted oleq s -> x \in s -> oleq x (last y s).
Lemma sorted_max_key_last (A : ordType) (s : seq A) x y : sorted oleq s -> x \in s -> (forall z, z \in s -> oleq z x) -> last y s = x.
Lemma seq_last_mono (A : ordType) (s1 s2 : seq A) x : path oleq x s1 -> path oleq x s2 -> {subset s1 <= s2} -> oleq (last x s1) (last x s2).