∀ {C : Type u₁} [inst : CategoryTheory.Category.{v₁, u₁} C] {D : Type u₂} [inst_1 : CategoryTheory.Category.{v₂, u₂} D]
  {E : Type u₃} [inst_2 : CategoryTheory.Category.{v₃, u₃} E] (F : CategoryTheory.Functor C D)
  {G : CategoryTheory.Functor D E} {e : E} (f : CategoryTheory.StructuredArrow e G),
  (CategoryTheory.StructuredArrow.preEquivalence F f).unitIso =
    CategoryTheory.NatIso.ofComponents
      (fun x =>
        CategoryTheory.StructuredArrow.isoMk
          (CategoryTheory.StructuredArrow.isoMk
            (CategoryTheory.Iso.refl
              ((CategoryTheory.Functor.id
                        (CategoryTheory.StructuredArrow f (CategoryTheory.StructuredArrow.pre e F G))).obj
                    x).right.right)
            ⋯)
          ⋯)
      ⋯