proposition: Lemma ccw2 p : ccw (ccw p) = Gpoint 1 1 - p.
proof: Proof. by case: p. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq path) mathcomp(div choice order ssralg ssrnum ssrint intdiv) fourcolor(hypermap)