proposition: Lemma nattrans_natequiv {A B : Type} `{IsGraph A} `{HasEquivs B} {F G : A -> B} `{!Is0Functor F, !Is0Functor G} : NatEquiv F G -> NatTrans F G.
proof: Proof. intros alpha. nrapply Build_NatTrans. rapply (is1natural_natequiv alpha). Defined.
imports: Basics.Overture Basics.Tactics WildCat.Core WildCat.Equiv WildCat.Square