∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {F G : CategoryTheory.Functor C (Type w')} (τ : F ⟶ G)
  [inst_1 : CategoryTheory.FunctorToTypes.Small.{w, w', v, u} F]
  [inst_2 : CategoryTheory.FunctorToTypes.Small.{w, w', v, u} G] (X : C)
  (a : (CategoryTheory.FunctorToTypes.shrink.{w, w', v, u} F).obj X),
  (CategoryTheory.FunctorToTypes.shrinkMap τ).app X a =
    (⇑(equivShrink (G.obj X)) ∘ τ.app X ∘ ⇑(equivShrink (F.obj X)).symm) a