code: def vrrp_config_change(app, instance_name,
                         priority=None, advertisement_interval=None,
                         preempt_mode=None, accept_mode=None):
      
      config_change = vrrp_event.EventVRRPConfigChangeRequest(
          instance_name, priority, advertisement_interval,
          preempt_mode, accept_mode)
      return app.send_event(vrrp_event.VRRP_MANAGER_NAME, config_change)
docs: change configuration of an instance.
      None means no change.