proposition: Lemma length_rev : forall l, length (rev l) = length l.
proof: Proof. Proof using. intros. induction~ l. { rewrite rev_cons. rew_list~. } Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)