code: func (store *MemoryStore) All() []string {
  	store.RLock()
  	defer store.RUnlock()
  	if !store.opened {
  		ERROR.Println(STR, "Trying to use memory store, but not open")
  		return nil
  	}
  	keys := []string{}
  	for k := range store.messages {
  		keys = append(keys, k)
  	}
  	return keys
  }
docs: // All returns a slice of strings containing all the keys currently
  // in the MemoryStore.