code: def delete(self):
          
          super(Interface, self).delete()
          for route in self._engine.routing:
              if route.to_delete:
                  route.delete()
          self._engine._del_cache()
docs: Override delete in parent class, this will also delete
          the routing configuration referencing this interface.
          ::
  
              engine = Engine('vm')
              interface = engine.interface.get(2)
              interface.delete()