case cons a as h_ind =>
  dsimp [joinF.unitorLeftLax, joinF.unitorLeftOplax]
  rw [h_ind, Category.id_comp]
  rfl
α : Type u
inst✝ : Category α
a : α
as : List α
h_ind : joinF.unitorLeftOplax as ≫ joinF.unitorLeftLax as = 𝟙 (Prefunctor.obj (singletonF ⋙ joinF).toPrefunctor as)
⊢ joinF.unitorLeftOplax (a :: as) ≫ joinF.unitorLeftLax (a :: as) =
    𝟙 (Prefunctor.obj (singletonF ⋙ joinF).toPrefunctor (a :: as))
no goals