fact: Definition opposite_functor (C D : PreCategory) : Functor (C -> D) (C^op -> D^op)^op := Build_Functor (C -> D) ((C^op -> D^op)^op) (fun F => F^op)%functor (fun _ _ T => T^op)%natural_transformation (fun _ _ _ _ _ => idpath) (fun _ => idpath).
imports: Category.Core Functor.Core NaturalTransformation.Core Category.Dual Functor.Dual NaturalTransformation.Dual Functor.Identity FunctorCategory.Core Functor.Paths HoTT.Tactics