def __new__(mcs, name, bases, params):
        source = params.get('source')
        cls = super(AlertFabric, mcs).__new__(mcs, name, bases, params)
        if source:
            mcs.alerts[source] = cls
            LOGGER.info('Register Alert: %s', source)
        return cls
Register an Alert Class in self.
dataset/ETHPy150Open klen/graphite-beacon/graphite_beacon/alerts.py/AlertFabric.__new__