anchor.diff:      install -D -m 755 k2pdfopt $out/bin/k2pdfopt
     '';
   
  +  preFixup = optionalString enableTesseract ''
  +    wrapProgram $out/bin/k2pdfopt --set-default TESSDATA_PREFIX ${tesseract4}/share/tessdata
  +  '';
  +
     meta = with stdenv.lib; {
       description = "Optimizes PDF/DJVU files for mobile e-readers (e.g. the Kindle) and smartphones";
       homepage = "http://www.willus.com/k2pdfopt";
  
positive.code:       --replace "<djvu.h>" "<libdjvu/ddjvuapi.h>"
    '';
  
    nativeBuildInputs = [ cmake pkgconfig ];
  
    buildInputs =
    let
  
negative.code: { stdenv, runCommand, fetchzip, fetchurl, fetchpatch, fetchFromGitHub
  , cmake, pkgconfig, zlib, libpng, makeWrapper
  , enableGSL ? true, gsl
  , enableGhostScript ? true, ghostscript
  , enableMuPDF ? true, mupdf
  