proposition: Lemma length_nat_seq : forall start nb, length (nat_seq start nb) = nb.
proof: Proof. Proof using. intros. gen start. induction nb; simpl; intros. { auto. } { rew_list. rewrite~ IHnb. } Qed.
imports: Coq.Classes.Morphisms TLC(LibTactics LibLogic LibReflect LibOperation LibProd LibOption LibNat LibInt LibWf LibMonoid LibRelation)