∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {X Y Z : C} {f : X ⟶ Y} {g : X ⟶ Z}
  (t : CategoryTheory.Limits.PushoutCocone f g),
  CategoryTheory.CategoryStruct.comp t.flip.flip.inr (CategoryTheory.Iso.refl t.flip.flip.pt).hom = t.inr