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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 is_expired(self, token, when=0):
 """ Evaluate whether the token has expired or not :param token: The token :param when: The time against which to check the expiration 0 means now. :return: True/False """

        verifier = JWT(key_jar=self.key_jar, allowed_sign_algs=[self.alg])
        _payload = verifier.unpack(token)
        return is_expired(_payload['exp'], when)