∀ {C : Type u} [inst : CategoryTheory.Category.{v, u} C] {F : CategoryTheory.Functor Cᵒᵖ (Type w)} {X : C}
  {x : F.obj (Opposite.op X)}, (∀ {Y : C}, Function.Bijective fun f => F.map f.op x) → F.IsRepresentedBy x