proposition: Lemma pvalE s : pval s = s :> (T -> T).
proof: Proof. by rewrite [@fun_of_perm]unlock. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(choice fintype tuple finfun bigop finset binomial) mathcomp(fingroup morphism)