fact: Definition equiv_postcompose_cat_equiv {A : Type} `{HasEquivs A} `{!HasMorExt A} {x y z : A} (f : y $<~> z) : (x $-> y) <~> (x $-> z) := emap (opyon x) f.
imports: Basics.Overture Basics.Tactics WildCat.Core WildCat.Equiv WildCat.Universe WildCat.Opposite WildCat.FunctorCat WildCat.NatTrans WildCat.Prod WildCat.ZeroGroupoid