proposition: Lemma cover_subset X F : measurable_cover X F -> X `<=` \bigcup_k (F k).
proof: Proof. by case. Qed.
imports: mathcomp(all_ssreflect all_algebra finmap) mathcomp(mathcomp_extra boolp classical_sets functions) mathcomp(cardinality fsbigop ) reals ereal signed topology normedtype sequences esum numfun HB(structures)