// MARK: - Single view
  mainView.signUpButton.tapPublisher
      .flatMap { [unowned self] _ in
          return SignUpViewController.instance().presentedWithNavigation(on: self).eraseToAnyPublisher()
      }.sink { [weak self] model in
          guard let self = self else { return }
          self.mainView.emailName.text = model.name
          self.mainView.passWordName.text = model.password
      }.store(in: &cancellables)

  // MARK: - ChainPresent
  mainView.chainButton.tapPublisher
      .flatMap { [unowned self] _ in
          // Email화면
          return SignUpEmailViewController.instance().presentedWithNavigation(on: self).eraseToAnyPublisher()
      }.flatMap { promiseData in
          // password 화면
          return SignUpPassWordViewController.instance(data: promiseData).pushViewController(animated: true).eraseToAnyPublisher()
      }.sink { [weak self] model in
          guard let self = self else { return }
          self.mainView.emailName.text = model.name
          self.mainView.passWordName.text = model.password
      }.store(in: &cancellables)