code: public SegmentedJournalReader<E> openReader(long index, SegmentedJournalReader.Mode mode) {
      SegmentedJournalReader<E> reader = new SegmentedJournalReader<>(this, index, mode);
      readers.add(reader);
      return reader;
    }
docs: Opens a new Raft log reader with the given reader mode.
  
  @param index The index from which to begin reading entries.
  @param mode The mode in which to read entries.
  @return The Raft log reader.