@Override
 public void aggregate(ByteBuffer buf, int position) {
   buf.putDouble(position, script.aggregate(buf.getDouble(position), selectorList));
 }
 @Override
 public void close() {
   script.close();
 }
 @Override
 public void init(ByteBuffer buf, int position) {
   buf.putDouble(position, script.reset());
 }