def add_extension(
        self, extval: ExtensionType, critical: bool
    ) -> CertificateRevocationListBuilder:
        """
        Adds an X.509 extension to the certificate revocation list.
        """
        if not isinstance(extval, ExtensionType):
            raise TypeError("extension must be an ExtensionType")

        extension = Extension(extval.oid, critical, extval)
        _reject_duplicate_extension(extension, self._extensions)
        return CertificateRevocationListBuilder(
            self._issuer_name,
            self._last_update,
            self._next_update,
            [*self._extensions, extension],
            self._revoked_certificates,
        )

        Adds an X.509 extension to the certificate revocation list.
        
Solutions/CyberArkAudit/Data Connectors/.python_packages/lib/site-packages/cryptography/x509/base.py