code: public static NavigableMap<String, Integer> loadVocab(InputStream is) throws IOException {
          final TreeMap<String, Integer> map = new TreeMap<>(Collections.reverseOrder());
  
          try (final BufferedReader reader = new BufferedReader(new InputStreamReader(is))) {
              String token;
              int i = 0;
              while ((token = reader.readLine()) != null) {
                  map.put(token, i++);
              }
          }
  
          return map;
      }
docs: The expected format is a \n seperated list of tokens for examples
  
  <code>
  foo
  bar
  baz
  </code>
  
  the tokens should <b>not</b> have any whitespace on either of their sides
  
  @param is InputStream
  @return A vocab map with the popper sort order for fast traversal