as described in Fan, X., Lamarre-Vincent, N., Wang, Q., and Struhl, K. (2008). Extensive chromatin fragmentation improves enrichment of protein binding sites in chromatin immunoprecipitation experiments. Nucl. Acids Res. 36, e125. as described in Wong, K.-H., Jin, Y., and Moqtaderi, Z. (2013). Multiplex Illumina sequencing using DNA barcoding. Curr Protoc Mol Biol Chapter 7, Unit 7.11.