code: func (bl *blackList) clear() {
  	for _ = range time.Tick(time.Minute * 10) {
  		keys := make([]interface{}, 0, 100)
  
  		for item := range bl.list.Iter() {
  			if time.Now().Sub(
  				item.val.(*blockedItem).createTime) > bl.expiredAfter {
  
  				keys = append(keys, item.key)
  			}
  		}
  
  		bl.list.DeleteMulti(keys)
  	}
  }
docs: // clear cleans the expired items every 10 minutes.