merge例子：

把兩個(gè)接口請(qǐng)求是否完成壓縮為一個(gè)信號(hào)再做操作

Observable.merge(viewModel.endAction.elements, viewModel.payAction.elements)
            .observeOn(MainScheduler.instance)
            .subscribe(onNext: { [weak self] model in
                if let bottomButton = self?.payMethodsView?.bottomButton {
                    bottomButton.isLoading = false
                    bottomButton.showSuccessLoading { [weak self] in
                        self?.pushEndViewController(model: model)
                    }
                } else {
                    self?.pushEndViewController(model: model)
                }
            })
            .disposed(by: disposeBag)