Some cleanup of cascade code
Some cleanup of cascade code

tgyhlsb/RxSwiftExt,RxSwiftCommunity/RxSwiftExt,tgyhlsb/RxSwiftExt,RxSwiftCommunity/RxSwift-Ext,RxSwiftCommunity/RxSwiftExt,RxSwiftCommunity/RxSwiftExt,RxSwiftCommunity/RxSwift-Ext