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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 crl(self):
 """ Returns up to date CRL of this CA """

        revoked_certs = self.get_revoked_certs()
        crl = crypto.CRL()
        now_str = timezone.now().strftime(generalized_time)
        for cert in revoked_certs:
            revoked = crypto.Revoked()
            revoked.set_serial(bytes_compat(cert.serial_number))
            revoked.set_reason(b'unspecified')
            revoked.set_rev_date(bytes_compat(now_str))
            crl.add_revoked(revoked)
        return crl.export(self.x509, self.pkey, days=1, digest=b'sha256')