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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 logged_in(f):
 """ Decorator for Page methods that require the user to be authenticated. """


    @wraps(f)
    def wrapped_method(self, *args, **kwargs):
        if not self.reddit.is_oauth_session():
            self.term.show_notification('Not logged in')
            return None
        return f(self, *args, **kwargs)
    return wrapped_method