class System {
    let authorizer: Authorizer
    var authorizedUser: User?

    init(with authorizer: Authorizer) {
        self.authorizer = authorizer
    }

    func recheckAuthorizedUser() {
        guard let user = authorizedUser else {
            return
        }

        if !authorizer.authorize(username: user.username, password: user.password) {
            // redirect to login page
        }
    }
}