∀ {A : Type u_1} {B : Type u_2} {C : Type u_3} {D : Type u_4} {inst : CategoryTheory.Category.{v_1, u_1} A}
  {inst_1 : CategoryTheory.Category.{v_2, u_2} B} {inst_2 : CategoryTheory.Category.{v_3, u_3} C}
  {inst_3 : CategoryTheory.Category.{v_4, u_4} D} {G : CategoryTheory.Functor B D} {F : CategoryTheory.Functor A B}
  {L : CategoryTheory.Functor A C} {c : C} [self : G.PreservesPointwiseLeftKanExtensionAt F L c] (E : L.LeftExtension F)
  (a : E.IsPointwiseLeftKanExtensionAt c),
  Nonempty (((CategoryTheory.Functor.LeftExtension.postcompose₂ L F G).obj E).IsPointwiseLeftKanExtensionAt c)