proposition: Lemma has_expC mu c : \E?_[mu] (fun _ => c).
proof: Proof. by apply/summableMl => //; exists `|c|. Qed.
imports: mathcomp(all_ssreflect all_algebra) mathcomp.classical(boolp classical_sets mathcomp_extra) xfinmap ereal reals discrete topology realseq realsum