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   A compressed data set consists of a series of blocks, corresponding
   to successive blocks of input data.  The block sizes are arbitrary,
   except that non-compressible blocks are limited to 65,535 bytes.

   Each block is compressed using a combination of the LZ77 algorithm
   and Huffman coding. The Huffman trees for each block are independent
   of those for previous or subsequent blocks; the LZ77 algorithm may
   use a reference to a duplicated string occurring in a previous block,
   up to 