docs: private void eval(List<Tuple> training, List<Tuple> testing, int nfold) {
          classifier.train(training);
  
          for (Tuple tuple : testing) {
              String actual = classifier.predict(tuple).entrySet().stream()
                      .max((e1, e2) -> e1.getValue().compareTo(e2.getValue()))
                      .map(Map.Entry::getKey).orElse(StringUtils.EMPTY);
              updateScore(tuple, actual, nfold);
          }
      }