∀ {C : Type u_1} {D : Type u_2} [inst : CategoryTheory.Category.{v_1, u_1} C]
  [inst_1 : CategoryTheory.Category.{v_2, u_2} D] (L : CategoryTheory.Functor C D) {H : Type u_3}
  [inst_2 : CategoryTheory.Category.{v_3, u_3} H] [inst_3 : ∀ (F : CategoryTheory.Functor C H), L.HasLeftKanExtension F]
  (G : CategoryTheory.Functor D H),
  (L.lanAdjunction H).counit.app G =
    (L.lan.obj (L.comp G)).descOfIsLeftKanExtension (L.lanUnit.app (L.comp G)) G
      (CategoryTheory.CategoryStruct.id (L.comp G))