def get_notification_result(self, stream_id):
        """
        Get result for specified stream
        The function returns: 'Success' or 'failure reason' or ('Unregistered', timestamp)
        """
        with self._connection.get_response(stream_id) as response:
            if response.status == 200:
                return 'Success'
            else:
                raw_data = response.read().decode('utf-8')
                data = json.loads(raw_data)
                if response.status == 410:
                    return data['reason'], data['timestamp']
                else:
                    return data['reason']
Get result for specified stream
        The function returns: 'Success' or 'failure reason' or ('Unregistered', timestamp)