proposition: Lemma intcompn1 (sh : intcompn 1) : sh = [:: 1] :> seq nat.
proof: Proof. case: sh => sh Hsh /=; move: Hsh; rewrite enum_compnP. by rewrite /enum_compn /= inE => /eqP. Qed.
imports: HB(structures) mathcomp(all_ssreflect) tools combclass sorted partition subseq ordtype