Improve ToAsync and Using usage
Improve ToAsync and Using usage

ReactiveX/RxCpp,Reactive-Extensions/RxCpp,ReactiveX/RxCpp,alexeymarkov/RxCpp,alexeymarkov/RxCpp,alexeymarkov/RxCpp,Reactive-Extensions/RxCpp,Reactive-Extensions/RxCpp,ReactiveX/RxCpp