def get_revoked_certificate_by_serial_number(self, serial_number):
        """
        Returns an instance of RevokedCertificate or None if the serial_number
        is not in the CRL.
        """

        Returns an instance of RevokedCertificate or None if the serial_number
        is not in the CRL.
        
stackoverflow/venv/lib/python3.6/site-packages/cryptography/x509/base.py