Method subpath

src/main/java/wycc/util/Trie.java:132–139

(int start, int end)

	}

	public Trie subpath(int start, int end) {
		Trie id = Trie.ROOT;
		for(int i=start;i!=end;++i) {
			// TODO: this could be made more efficient
			id = id.append(get(i));
		}
		return id;
	}
	public Trie parent(int depth) {
		if(this.depth < depth) {
			return this;