static void parseUrl(String url, StringBuilder buf){
        int index = 0;
        char urlCharacter = url.charAt(index);
        while (index < url.length()) {
            if (!isIndexable(urlCharacter)) {
                index++;
                continue;
            }

            int wordEndIndex = index;
            while (wordEndIndex < url.length() && isIndexable(url.charAt(wordEndIndex))) {
                wordEndIndex++;
            }

            if(index != wordEndIndex){
                buf.append(url.substring(index, wordEndIndex).toLowerCase()).append(" U\n");
            }
            index = wordEndIndex + 1;
        }
    }