code: def delete_invalid_route(self):
          
          try:
              routing = self._engine.routing.get(self.interface_id)
              for route in routing:
                  if route.invalid or route.to_delete:
                      route.delete()
          except InterfaceNotFound: # Only VLAN identifiers, so no routing
              pass
docs: Delete any invalid routes for this interface. An invalid route is
          a left over when an interface is changed to a different network.
          
          :return: None