(** Opposite of NatTrans_id is just NatTrans_id of the opposite functor *)
Section NatTrans_id_Op.
Context {C D : Category} (F : (C –≻ D)%functor).

Theorem NatTrans_id_Op
: ((NatTrans_id F)^op)%nattrans = NatTrans_id (F^op)%functor.