proposition: Lemma collb_refl x : collb x x.
proof: Proof. apply/collP. rewrite /coll. auto. Qed.
imports: HB(structures) mathcomp(ssreflect ssrfun ssrbool eqtype ssrnat seq choice) mathcomp(fintype path fingraph finfun finset generic_quotient) RegLang(misc languages dfa)