fact: Definition yon_cancel {A : Type} `{Is01Cat A} (a b : A) : (yon a $=> yon b) -> (a $-> b) := un_yoneda a (yon b).
imports: Basics.Overture Basics.Tactics WildCat.Core WildCat.Equiv WildCat.Universe WildCat.Opposite WildCat.FunctorCat WildCat.NatTrans WildCat.Prod WildCat.ZeroGroupoid