code: func (idx *TruncIndex) Iterate(handler func(id string)) {
  	idx.Lock()
  	defer idx.Unlock()
  	idx.trie.Visit(func(prefix patricia.Prefix, item patricia.Item) error {
  		handler(string(prefix))
  		return nil
  	})
  }
docs: // Iterate iterates over all stored IDs and passes each of them to the given
  // handler. Take care that the handler method does not call any public
  // method on truncindex as the internal locking is not reentrant/recursive
  // and will result in deadlock.