override func navigate(to step: AppStep) -> StepAction {
        switch step {
        case .showFirstViewController(let animated):
            let firstViewController = DocumentBrowserViewController(forOpeningFilesWithContentTypes: ["two", "one"])
            return .push(firstViewController)

        case .showSecondViewController(let animated):
            let secondViewController = DocumentBrowserViewController(forOpeningFilesWithContentTypes: ["hone", "two"])
            return .push(secondViewController)

        default:
            return .none
        }

    }