∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] [inst_1 : CategoryTheory.Limits.HasZeroMorphisms C]
  {X Y : Cᵒᵖ} (f : X ⟶ Y) (m : CategoryTheory.NormalMono f.unop),
  CategoryTheory.CategoryStruct.comp f.unop CategoryTheory.NormalMono.g = 0