∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {X Y Z : C} (α : X ≅ Y) (β : Y ≅ Z),
  α ≪≫ β =
    { hom := CategoryTheory.CategoryStruct.comp α.hom β.hom, inv := CategoryTheory.CategoryStruct.comp β.inv α.inv,
      hom_inv_id := ⋯, inv_hom_id := ⋯ }