anchor.diff:  
     nativeBuildInputs = [ pkg-config ];
     buildInputs = [ freetype harfbuzz openjpeg jbig2dec libjpeg gumbo ]
  +    ++ lib.optional stdenv.isDarwin xcbuild
       ++ lib.optionals enableX11 [ libX11 libXext libXi libXrandr ]
       ++ lib.optionals enableCurl [ curl openssl ]
       ++ lib.optionals enableGL (
  
positive.code: , enableGL ? true
  , freeglut
  , libGLU
  }:
  let
  
  
negative.code:     sha256 = "1vfyhlqq1a0k0drcggly4bgsjasmf6lmpfbdi5xcrwdbzkagrbr1";
    };
  
    patches = [ ./0001-Use-command-v-in-favor-of-which.patch
                ./0002-Add-Darwin-deps.patch
              ];
  
    postPatch = ''
      sed -i "s/__OPENJPEG__VERSION__/${openJpegVersion}/" source/fitz/load-jpx.c
  