anchor.diff:  { lib, stdenv
   , go
   , fetchurl
  +, redo-apenwarr
   , curl
   , perl
   , genericUpdater
  
positive.code:       transmission exists.
      '';
      homepage = "http://www.nncpgo.org/";
      license = licenses.gpl3;
      platforms = platforms.all;
      maintainers = [ maintainers.woffs ];
    };
  
negative.code: 
  stdenv.mkDerivation rec {
    pname = "nncp";
    version = "6.2.0";
  
    src = fetchurl {
      url = "http://www.nncpgo.org/download/${pname}-${version}.tar.xz";
      sha256 = "1zj0v82zqigcxhpc50mvafvi1ihs92ck35vjfrwb7wzzd7nysb17";
    };
  
    nativeBuildInputs = [ go redo-apenwarr ];
  
    buildPhase = ''
      runHook preBuild
      export GOCACHE=$PWD/.cache
      export CFGPATH=/etc/nncp.hjson
      export SENDMAIL=sendmail # default value for generated config file
      redo ''${enableParallelBuilding:+-j''${NIX_BUILD_CORES}}
      runHook postBuild
    '';
  
    installPhase = ''
      runHook preInstall
      export PREFIX=$out
      rm -f INSTALL # work around case insensitivity
      redo install
      runHook postInstall
    '';
  
    enableParallelBuilding = true;
  
    passthru.updateScript = genericUpdater {
      inherit pname version;
  