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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 expires(self):
 """ The date and time after which the certificate will be considered invalid. """

        not_after = self._cert.get_notAfter().decode('ascii')
        return datetime.datetime.strptime(not_after, '%Y%m%d%H%M%SZ').replace(
            tzinfo=datetime.timezone.utc)