∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] (F : CategoryTheory.Functor C (Type w)) {X Y Z : C} (p : X = Y)
  (q : Y = Z) (x : F.obj X),
  F.map (CategoryTheory.eqToHom q) (F.map (CategoryTheory.eqToHom p) x) = F.map (CategoryTheory.eqToHom ⋯) x