lazy var printName: ()->() = {
	    print("The name is \(self.name)")
	    //        The name is XiaoMing
	    //        Optional(A4Paper.Person)
	    //        nil
	}

	//    lazy var printName: ()->() = { [unowned self] in
	//        print("The name is \(self.name)")
	//        //        The name is XiaoMing
	//        //        Optional(A4Paper.Person)
	//        //        Person deinit XiaoMing
	//        //        nil
	//    }

	//    lazy var printName: ()->() = { [weak self] in
	//        guard let strongSelf = self else {
	//            return
	//        }
	//        print("The name is \(strongSelf.name)")
	////        The name is XiaoMing
	////        Optional(A4Paper.Person)
	////        Person deinit XiaoMing
	////        nil
	//    }

	func printName() {
	//            Singleton.default.block = { print("The name is \(self.name)")}
	    Singleton.default.block = { [unowned self] in print("The name is \(self.name)") }
	//            Singleton.default.block = { [weak self] in print("The name is \(String(describing: self?.name))") }
	    Singleton.default.callBlockAsync()


	    // 1 nothing to do
	    /*
	    Optional(A4Paper.BlockSelf.Person)
	    nil
	    */

	    // 2 unowned self
	    /*
	    Optional(A4Paper.BlockSelf.Person)
	    Person deinit XiaoMing
	    Person deinit A4Paper.BlockSelf.Person
	    nil
	    Fatal error: Attempted to read an unowned reference but object 0x600002b36610 was already deallocated2018-10-30 09:43:09.887756+0800 A4Paper[3951:76031] Fatal error: Attempted to read an unowned reference but object 0x600002b36610 was already deallocated
	     */

	    // 3 weak self
	    /*
	    Optional(A4Paper.BlockSelf.Person)
	    Person deinit XiaoMing
	    Person deinit A4Paper.BlockSelf.Person
	    nil
	    */
	}