∀ {M N P : Type u} [inst : Add M] [inst_1 : Add N] [inst_2 : Add P] (f : M →ₙ+ N) (g : N →ₙ+ P),
  AddMagmaCat.ofHom (g.comp f) = CategoryTheory.CategoryStruct.comp (AddMagmaCat.ofHom f) (AddMagmaCat.ofHom g)