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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def login_required(self, fresh=False, redirect_to=None):
 """Ensures that a user is authenticated """

        if not self.logged_in() or (fresh and not self.login_manager.login_fresh()):
            if redirect_to:
                resp = redirect(redirect_to)
            else:
                resp = self.login_manager.unauthorized()
            current_context.exit(resp, trigger_action_group="missing_user")