code: public static double score(MultiLayerNetwork model, DataSetIterator testSet, RegressionValue regressionValue) {
          RegressionEvaluation eval = model.evaluateRegression(testSet);
          return getScoreFromRegressionEval(eval, regressionValue);
      }
docs: Score the given multi layer network
  @param model the model to score
  @param testSet the test set
  @param regressionValue the regression function to use
  @return the score from the given test set