proposition: Lemma msum_mzero d (T : measurableType d) (R : realType) (m_ : {measure set T -> \bar R}^nat) : msum m_ 0 = mzero.
proof: Proof. by apply/funext => A/=; rewrite /msum big_ord0. 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)