∀ {G : Type u_2} [inst : CategoryTheory.Groupoid G] (F : CategoryTheory.Functor G (Type u_3)) {X Y : F.Elements}
  (x : X ⟶ Y),
  CategoryTheory.CategoryStruct.comp x ⟨CategoryTheory.Groupoid.inv ↑x, ⋯⟩ = CategoryTheory.CategoryStruct.id X