code: func (c *Client) SendLabelManagerConnectAsync() error {
  	if c.Version < 5 {
  		return fmt.Errorf("LABEL_MANAGER_CONNECT_ASYNC is not supported in zebra API version: %d", c.Version)
  	}
  	command := FRR_ZAPI5_LABEL_MANAGER_CONNECT_ASYNC
  	proto := FRR_ZAPI5_ROUTE_BGP
  	if c.Version == 6 {
  		command = FRR_ZAPI6_LABEL_MANAGER_CONNECT_ASYNC
  		proto = FRR_ZAPI6_ROUTE_BGP
  	}
  	return c.SendCommand(
  		command, 0,
  		&LabelManagerConnectBody{
  			RedistDefault: proto,
  			Instance:      0,
  		})
  }
docs: // Reference: zread_label_manager_connect function in zebra/zserv.c of FRR3.x (ZAPI)
  // Reference: zread_label_manager_connect function in zebra/zapi_msg.c of FRR5.x and 6.x (ZAPI5 and 6)