class MergeCursor extends MapCursor {

    @Override
    public LazyRecord next() throws IOException, InterruptedException
    {
        LazyRecord next = null;
        if (state != State.DONE) {
            if (!forward) {
                restartAtStartKey(true);
            }
            next = neighbor();
        }
        return next;
    }

    public  MergeCursor(AbstractKey startKey, boolean forward);
      MergeCursor(Merger merger, AbstractKey startKey, boolean forward);

}