code: func (m *Message) UpdateEventsID(db *mgo.Database, eventID ...string) error {
  	m.EventID = append(m.EventID, eventID...)
  	f := bson.M{"botid": m.BotID}
  	if m.InlineMsgID != "" {
  		f["inlinemsgid"] = m.InlineMsgID
  	} else {
  		f["chatid"] = m.ChatID
  		f["msgid"] = m.MsgID
  	}
  	return db.C("messages").Update(f, bson.M{"$addToSet": bson.M{"eventid": bson.M{"$each": eventID}}})
  }
docs: // UpdateEventsID sets the event id and update it in DB