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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 notify_observers(self, event=None, msg=None):
 """Notify observers."""

        for observer, events in list(self._observers.items()):
            # LOG.debug("trying to notify the observer")
            if events is None or event is None or event in events:
                try:
                    observer(self, event, msg)
                except (Exception,) as ex:  # pylint: disable=broad-except
                    self.unregister_observer(observer)
                    errmsg = "Exception in message dispatch: Handler '{0}' unregistered for event '{1}'  ".format(
                        observer.__class__.__name__, event)
                    LOG.error(errmsg, exc_info=ex)