docs: public <Type extends DataSet> OnLineStatistics[] evaluateFeatureImportance(DataSet<Type> data, TreeFeatureImportanceInference imp)
      {
          OnLineStatistics[] importances = new OnLineStatistics[data.getNumFeatures()];
          for(int i = 0; i < importances.length; i++)
              importances[i] = new OnLineStatistics();
          
          for(ExtraTree tree :forrest)
          {
              double[] feats = imp.getImportanceStats(tree, data);
              for(int i = 0; i < importances.length; i++)
                  importances[i].add(feats[i]);
          }
          
          return importances;
      }