code: public static SimpleStringTrie from(Map<String,?> map) {
          SimpleStringTrie st = new SimpleStringTrie();
          map.keySet().forEach(key -> st.add(key));
          return st;
      }
docs: Useful if you want to build a trie for an existing map so you can figure out a matching prefix that has an entry
  @param map a map
  @return a SimpleStringTrie for the map.