@Override
 public void setFeatureWindowSize(int size) {
   source.setFeatureWindowSize(size);
 }
 @Override
 public List<LocusScore> getCoverageScores(String chr, int start, int end, int zoom) {
   return source.getCoverageScores(chr, start, end, zoom);
 }
 @Override
 public int getFeatureWindowSize() {
   return source.getFeatureWindowSize();
 }
 @Override
 protected Iterator<Feature> queryRaw(String chr, int start, int end) throws IOException {
   return source.getFeatures(chr, start, end);
 }