∀ {T : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} T] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  (F : CategoryTheory.Functor T D) (Y : D) (X : T)
  (Y_1 : CategoryTheory.CostructuredArrow (CategoryTheory.CostructuredArrow.proj F Y) X),
  ((CategoryTheory.CostructuredArrow.ofCostructuredArrowProjEquivalence.functor F Y X).obj Y_1).left.right.as =
    PUnit.unit