anchor.diff:      plibs=`pwd`/patched_libraries
   
       tar zxf ${mupdf_src}
  -    cp $src/mupdf_mod/font.c $src/mupdf_mod/string.c mupdf-1.5-source/source/fitz/
  -    cp $src/mupdf_mod/pdf-* mupdf-1.5-source/source/pdf
  +    cp $src/mupdf_mod/font.c $src/mupdf_mod/string.c mupdf-1.6-source/source/fitz/
  +    cp $src/mupdf_mod/pdf-* mupdf-1.6-source/source/pdf
   
       tar zxf ${tess_src}
       cp $src/tesseract_mod/dawg.cpp tesseract-ocr/dict
  
positive.code: 
  let
    mupdf_src = fetchurl {
      url = http://www.mupdf.com/downloads/archive/mupdf-1.5-source.tar.gz;
      sha256 = "0sl47zqf4c9fhs4h5zg046vixjmwgy4vhljhr5g4md733nash7z4";
    };
  
    tess_src = fetchurl {
  
negative.code: 
  in stdenv.mkDerivation rec {
    name = "k2pdfopt-${version}";
    version = "2.32";
    src = fetchzip {
      url = "http://www.willus.com/k2pdfopt/src/k2pdfopt_v${version}_src.zip";
      sha256 = "1v3cj5bwpjvy7s66sfqcmkxs91f7nxaykjpdjm2wn87vn6q7n19m";
    };
  
    buildInputs = [ libX11 libXext autoconf automake libtool leptonica libpng libtiff zlib
  