proposition: Lemma mod2_S_S : forall n, mod2 (S (S n)) = mod2 n.
proof: Proof. intros. destruct n; auto; destruct n; auto. Qed.
imports: Coq.Classes.Morphisms Coq.Classes.Morphisms_Prop Coq.Bool.Bool Coq.Arith.Arith Coq.micromega.Lia Coq.NArith.NArith Coq.ZArith.ZArith bbv.N_Z_nat_conversions bbv.Nomega