{A} `{HasEquivs A} {a b : A} (f : a $<~> b) : cate_fun (f $oE id_cate a) $== cate_fun f := compose_cate_idl (A:=A^op) (a:=b) (b:=a) f.
Require Import Basics.Utf8 Basics.Overture Basics.Tactics Basics.Equivalences. Require Import WildCat.Core. Require Import WildCat.Opposite.