code: @Nullable
    public AnalyzedTokenReadings lookup(String word) throws IOException {
      List<AnalyzedTokenReadings> result = tag(Collections.singletonList(word), false);
      AnalyzedTokenReadings atr = result.get(0);
      if (atr.getAnalyzedToken(0).getPOSTag() == null) {
        return null;
      }
      return atr;
    }
docs: Return only the first reading of the given word or {@code null}.