code: func (db *cachingDB) CopyTrie(t Trie) Trie {
  	switch t := t.(type) {
  	case *trie.SecureTrie:
  		return t.Copy()
  	default:
  		panic(fmt.Errorf("unknown trie type %T", t))
  	}
  }
docs: // CopyTrie returns an independent copy of the given trie.