anchor.diff: -{ fetchurl, stdenv,
  -  cmake, netcdf, gfortran, jasper, libpng,
  +{ fetchurl, fetchpatch, stdenv,
  +  cmake, netcdf, gfortran, libpng, openjpeg,
     enablePython ? false, pythonPackages }:
   
   stdenv.mkDerivation rec{
  
positive.code:     sha256 = "0qbj12ap7yy2rl1pq629chnss2jl73wxdj1lwzv0xp87r6z5qdfl";
    };
  
    preConfigure = ''
      # Fix "no member named 'inmem_' in 'jas_image_t'"
      substituteInPlace "src/grib_jasper_encoding.c" --replace "image.inmem_    = 1;" ""
  
negative.code:   cmakeFlags = [ "-DENABLE_PYTHON=${if enablePython then "ON" else "OFF"}"
                   "-DENABLE_PNG=ON"
                   "-DENABLE_FORTRAN=ON"
                   "-DOPENJPEG_INCLUDE_DIR=${openjpeg.dev}/include/${openjpeg.incDir}"
                 ];
  
    enableParallelBuilding = true;
  