proposition: Lemma size_insub_bseq n T (s : seq T) : size (insub_bseq n s) <= size s.
proof: Proof. by rewrite /insub_bseq /insubd; case: insubP => // ? ? ->. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat) mathcomp(seq choice fintype path)