anchor.diff:      sed -i $dev/lib/pkgconfig/opencv.pc -e "s|includedir_new=.*|includedir_new=$dev/include|"
     '';
   
  -  passthru = lib.optionalAttrs enablePython { pythonPath = []; };
  -
     meta = with lib; {
       description = "Open Computer Vision Library with more than 500 algorithms";
       homepage = "https://opencv.org/";
  
positive.code:     ++ lib.optional enableEigen eigen
      ++ lib.optionals stdenv.isDarwin [ Cocoa QTKit ]
      ;
  
    propagatedBuildInputs = lib.optional enablePython python2Packages.numpy;
  
    nativeBuildInputs = [ cmake pkg-config unzip ];
  
  
negative.code: { lib, stdenv, fetchFromGitHub, cmake, pkg-config, unzip
  , zlib
  , enableGtk2 ? false, gtk2
  , enableJPEG ? true, libjpeg
  , enablePNG ? true, libpng
  