∀ {W X Y Z : FintypeCat.Skeleton} (f : ULift.{u_1, 0} (Fin W.len) → ULift.{u_1, 0} (Fin X.len))
  (g : ULift.{u_1, 0} (Fin X.len) → ULift.{u_1, 0} (Fin Y.len))
  (h : ULift.{u_1, 0} (Fin Y.len) → ULift.{u_1, 0} (Fin Z.len)), h ∘ g ∘ f = (h ∘ g) ∘ f