Add clone() & improve try() using recursive-call.
Add clone() & improve try() using recursive-call.

marinehero/SwiftTask,luzefeng/SwiftTask,msdgwzhy6/SwiftTask,ReactKit/SwiftTask,msdgwzhy6/SwiftTask,marinehero/SwiftTask,luzefeng/SwiftTask,ReactKit/SwiftTask,ReactKit/SwiftTask,iosyoujian/SwiftTask,iosyoujian/SwiftTask,luzefeng/SwiftTask,msdgwzhy6/SwiftTask,iosyoujian/SwiftTask,iosyoujian/SwiftTask,marinehero/SwiftTask,luzefeng/SwiftTask,marinehero/SwiftTask,msdgwzhy6/SwiftTask