code: private void score0(double[] data, double[] preds, int treeIdx) {
      Key[] keys = _output._treeKeys[treeIdx];
      for( int c=0; c<keys.length; c++ ) {
        if (keys[c] != null) {
          double pred = DKV.get(keys[c]).<CompressedTree>get().score(data,_output._domains);
          assert (!Double.isInfinite(pred));
          preds[keys.length == 1 ? 0 : c + 1] += pred;
        }
      }
    }
docs: Score per line per tree