∀ {C : Type u_2} [inst : CategoryTheory.Category.{u_1, u_2} C] {X Y : C} {f g : X ⟶ Y}
  {s t : CategoryTheory.Limits.Fork f g} (i : s.pt ≅ t.pt) (w : CategoryTheory.CategoryStruct.comp i.hom t.ι = s.ι),
  CategoryTheory.CategoryStruct.comp (CategoryTheory.Limits.Fork.mkHom i.hom w)
      (CategoryTheory.Limits.Fork.mkHom i.inv ⋯) =
    CategoryTheory.CategoryStruct.id s