code: func (hm *SyncedHashMap) Keys() (ch chan Hashable) {
  	ch = make(chan Hashable)
  	go func() {
  		hm.RLock()
  		defer hm.RUnlock()
  		defer close(ch)
  		for _, v := range hm.keys {
  			ch <- v
  		}
  	}()
  	return
  }
docs: // Keys returns a channel of Keys used by the HashMap