proposition: Lemma summable_has_exp mu F : summable F -> \E?_[mu] F.
proof: Proof. move=> smF; apply/summableMr => //; exists 1. by move=> x; rewrite ger0_norm // le1_mu1. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp classical_sets mathcomp_extra) xfinmap ereal reals discrete topology realseq realsum