{A B : Type} `{IsGraph A} `{HasEquivs B} (F G : A -> B) `{!Is0Functor F, !Is0Functor G} : _ <~> NatEquiv F G := ltac:(issig).
Require Import Basics.Overture Basics.Tactics. Require Import WildCat.Core. Require Import WildCat.Equiv. Require Import WildCat.Square. Require Import WildCat.Opposite.