code: public static Map<String, String> extractBrownFeat(String word) {
          if (!BROWN_CLUSTER.containsKey(word)) {
              return new HashMap<>();
          }
  
          String clusterId = BROWN_CLUSTER.get(word);
  
          return Arrays.stream(BROWN_PREFIX).mapToObj(p -> {
              int end = Math.min(p, clusterId.length());
              return new AbstractMap.SimpleEntry<>("brown_" + p, clusterId.substring(0, end));
          }).collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));
  
      }
docs: k: feat key - v: cluster Id