def METHOD_NAME(self, certificate, request_id=None, reason=None):
    """
    Revoke the specified certificate. At this point only the database
    index.txt is updated.
    :param certificate: The certificate to revoke
    :type certificate: Either takes X509 object or a PEM encoded
        certificate (string)
    :param request_id: The Id of the certificate in the certificate authority
    :type request_id: int
    :param reason: One of the available reasons the certificate gets revoked
    :type reason: basestring
    :return: Returns the serial number of the revoked certificate. Otherwise
        an error is raised.
    """
    pass