code: public static Pair<Long, Integer> parseStreamChunkId(String streamChunkId) {
      String[] array = streamChunkId.split("_");
      assert array.length == 2:
        "Stream id and chunk index should be specified.";
      long streamId = Long.valueOf(array[0]);
      int chunkIndex = Integer.valueOf(array[1]);
      return ImmutablePair.of(streamId, chunkIndex);
    }
docs: stream.