anchor.diff:    enableParallelBuilding = true;
   
     meta = with stdenv.lib; {
  +    inherit version;
       description = "Quickly find duplicate files";
  -    homepage = http://duff.dreda.org/;
  -    license = licenses.zlib;
       longDescription = ''
         Duff is a Unix command-line utility for quickly finding duplicates in
         a given set of files.
       '';
  +    homepage = http://duff.dreda.org/;
  +    license = licenses.zlib;
  +    platforms = platforms.all;
       maintainers = with maintainers; [ nckx ];
  -    platforms = with platforms; all;
     };
   }
  
positive.code: { stdenv, fetchFromGitHub, autoreconfHook, gettext }:
  
  let version = "0.5.2"; in
  stdenv.mkDerivation {
    name = "duff-${version}";
  
    src = fetchFromGitHub {
      sha256 = "0yfm910wjj6z0f0cg68x59ykf4ql5m49apzy8sra00f8kv4lpn53";
      rev = version;
      repo = "duff";
      owner = "elmindreda";
    };
  
negative.code:   nativeBuildInputs = [ autoreconfHook gettext ];
  
    preAutoreconf = ''
      # gettexttize rightly refuses to run non-interactively:
      cp ${gettext}/bin/gettextize .
      substituteInPlace gettextize \
  