code: func (trie *Trie) Clone() *Trie {
  	return &Trie{
  		prefix:                   append(Prefix(nil), trie.prefix...),
  		item:                     trie.item,
  		maxPrefixPerNode:         trie.maxPrefixPerNode,
  		maxChildrenPerSparseNode: trie.maxChildrenPerSparseNode,
  		children:                 trie.children.clone(),
  	}
  }
docs: // Clone makes a copy of an existing trie.
  // Items stored in both tries become shared, obviously.