∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  (F : CategoryTheory.Functor C D) {X Y Z : C} (p : X = Y) (q : Y = Z) {Z_1 : D} (h : F.obj Z ⟶ Z_1),
  CategoryTheory.CategoryStruct.comp (F.map (CategoryTheory.eqToHom p))
      (CategoryTheory.CategoryStruct.comp (F.map (CategoryTheory.eqToHom q)) h) =
    CategoryTheory.CategoryStruct.comp (F.map (CategoryTheory.eqToHom ⋯)) h