∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y Z : C} (α : Y ⟶ X) [inst_1 : CategoryTheory.IsIso α]
  {f : Z ⟶ X} {g : Z ⟶ Y},
  (CategoryTheory.CategoryStruct.comp f (CategoryTheory.inv α) = g) = (f = CategoryTheory.CategoryStruct.comp g α)