proposition: Lemma sort_le_id s : sorted <=%O s -> sort <=%O s = s.
proof: Proof. exact/sorted_sort/le_trans. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(path fintype tuple bigop finset div prime finfun) mathcomp(finset)