code: public static <I, O> SequenceTaggerError evaluateTagger(SequenceTagger<I, O> tagger,
        Collection<? extends TaggedSequence<I, O>> evaluationData) {
      MapReduceExecutor executor = MapReduceConfiguration.getMapReduceExecutor();
      return executor.mapReduce(evaluationData, new SequenceTaggerEvaluationMapper<I, O>(tagger, -1),
          new SequenceTaggerEvaluationReducer());
    }
docs: Evaluates the performance of {@code tagger} on
  {@code evaluationData}, returning both per-item and per-sequence
  error rates.
  
  @param tagger
  @param evaluationData
  @return