def subscribe(self):
        for channel in self.bus.listeners:
            # Subscribe self.start, self.exit, etc. if present.
            method = getattr(self, channel, None)
            if method is not None:
                self.bus.subscribe(channel, method)
Serialize a reason trail related to an instance change of state to file.
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/cherrypy/cherrypy/process/plugins.py/SimplePlugin.subscribe--crossover with--dataset/ETHPy150Open ganeti/ganeti/lib/backend.py/_StoreInstReasonTrail