proposition: Lemma rev_snipr_ring_eq : map snipr rev_snipr_ring = map edge r.
proof: Proof. by rewrite /rev_snipr_ring map_snipr_ring revK. Qed.
imports: mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph) fourcolor(hypermap geometry patch sew snip color chromogram) fourcolor(coloring kempe)