proposition: Lemma distSn n : `|n.+1 - n| = 1.
proof: Proof. exact: distnDr n 1 0. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat choice seq) mathcomp(fintype finfun bigop order ssralg countalg ssrnum) mathcomp(poly)