proposition: Lemma cardE (A : {pred T}) : #|A| = size (enum A).
proof: Proof. by rewrite size_sort cardE. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)