fact: Definition functor_opp {C D : precategory} (F : functor C D) : functor C^op D^op := tpair _ _ (is_functor_functor_opp F).
imports: UniMath.Foundations.PartD UniMath.Foundations.Propositions UniMath.MoreFoundations.All UniMath.CategoryTheory.Core.Categories UniMath.CategoryTheory.Core.Isos UniMath.CategoryTheory.Core.NaturalTransformations UniMath.CategoryTheory.Core.Univalence UniMath.CategoryTheory.Core.Functors UniMath.CategoryTheory.FunctorCategory