proposition: Lemma clopenT {T} : clopen [set: T].
proof: Proof. by split; [exact: openT | exact: closedT]. Qed.
imports: HB(structures) mathcomp(all_ssreflect all_algebra finmap generic_quotient) mathcomp(boolp classical_sets functions) mathcomp(cardinality mathcomp_extra fsbigop) reals signed