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