∀ {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] (F : CategoryTheory.Functor C H)
  [inst_3 : L.HasPointwiseLeftKanExtension F] (X : C),
  CategoryTheory.CategoryStruct.comp ((L.leftKanExtensionUnit F).app X)
      (L.leftKanExtensionObjIsoColimit F (L.obj X)).hom =
    CategoryTheory.Limits.colimit.ι ((CategoryTheory.CostructuredArrow.proj L (L.obj X)).comp F)
      (CategoryTheory.CostructuredArrow.mk (CategoryTheory.CategoryStruct.id (L.obj X)))