proposition: Lemma add_S_l a b : S a + b =N= S (a + b).
proof: Proof. exact idpath. Qed.
imports: HoTT.Classes.interfaces.abstract_algebra HoTT.Classes.interfaces.naturals HoTT.Classes.interfaces.orders HoTT.Classes.theory.rings HoTT.Classes.orders.semirings HoTT.Classes.theory.apartness