∀ {C : Type u_1} {H : Type u_3} {D : Type u_4} [inst : CategoryTheory.Category.{v_1, u_1} C]
  [inst_1 : CategoryTheory.Category.{v_3, u_3} H] [inst_2 : CategoryTheory.Category.{v_4, u_4} D]
  {F' : CategoryTheory.Functor D H} {L : CategoryTheory.Functor C D} {F : CategoryTheory.Functor C H}
  {α : L.comp F' ⟶ F},
  Nonempty (CategoryTheory.CostructuredArrow.IsUniversal (CategoryTheory.Functor.RightExtension.mk F' α)) →
    F'.IsRightKanExtension α