code: private void init() throws IOException {
          bsPutUByte('B');
          bsPutUByte('Z');
  
          this.data = new Data(this.blockSize100k);
          this.blockSorter = new BlockSort(this.data);
  
          // huffmanised magic bytes
          bsPutUByte('h');
          bsPutUByte('0' + this.blockSize100k);
  
          this.combinedCRC = 0;
          initBlock();
      }
docs: Writes magic bytes like BZ on the first position of the stream
  and bytes indiciating the file-format, which is
  huffmanised, followed by a digit indicating blockSize100k.
  @throws IOException if the magic bytes could not been written