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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 _start_loop(self):
 """Starts main event handler loop, run in handler thread t."""

        # Create our main loop, get our bus, and add the signal handler
        loop = GObject.MainLoop()
        bus = SystemBus()
        manager = bus.get(".NetworkManager")
        manager.onPropertiesChanged = self._vpn_signal_handler

        # Loop forever
        loop.run()