code: public static <I, O> PredictorTrainer<I, O> constant(O outputValue) {
      return new WrapperTrainer<I, O>(Predictors.<I, O>constant(outputValue));
    }
docs: Gets a {@code PredictorTrainer} which returns a predictor that puts all of
  its probability mass on {@code outputValue}. This predictor is returned
  regardless of the training data given to the trainer.
  
  @param outputValue
  @return