∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {X Y : C} (f : X ⟶ Y) (x : Cᵒᵖ)
  (g :
    { obj := fun Y => Opposite.unop Y ⟶ X, map := fun {X_1 Y} f g => CategoryTheory.CategoryStruct.comp f.unop g,
          map_id := ⋯, map_comp := ⋯ }.obj
      x),
  (CategoryTheory.yoneda.map f).app x g = CategoryTheory.CategoryStruct.comp g f