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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def invoke_webhook_handlers(self):
 		""" 		Invokes any webhook handlers that have been registered for this event 		based on event type or event sub-type. 		See event handlers registered in the ``djstripe.event_handlers`` module 		(or handlers registered in djstripe plugins or contrib packages). 		"""


		webhooks.call_handlers(event=self)

		signal = WEBHOOK_SIGNALS.get(self.type)
		if signal:
			return signal.send(sender=Event, event=self)