code: def register_properties_handler(self, handler_function):
          
  
          handler = filter_properties_signals(
              signal_wrapper(handler_function), self.IFACE)
  
          self.bus.add_signal_receiver(handler,
                                       signal_name='PropertiesChanged',
                                       dbus_interface=IPROPERTIES,
                                       bus_name=self.name,
                                       path=self.OBJ_PATH)
docs: register `handler_function` to receive `signal_name`.
  
          Uses dbus interface IPROPERTIES and objects path self.OBJ_PATH
          to match 'PropertiesChanged' signal.
  
          :param function handler_function: The function to be called.