anchor.diff:    # : lines
   , postInstall
     # : list Maintainer
  -, maintainers ? []
  +, maintainers ? [ ]
     # : passtrhu arguments (e.g. tests)
  -, passthru ? {}
  +, passthru ? { }
   
   }:
   
  
positive.code:     # binary built on a different version of darwin.
      # http://www.skarnet.org/cgi-bin/archive.cgi?1:mss:623:heiodchokfjdkonfhdph
      ++ (lib.optional stdenv.isDarwin
           "--build=${stdenv.hostPlatform.system}");
  
    inherit postConfigure;
  
    makeFlags = lib.optional stdenv.cc.isClang [ "AR=${stdenv.cc.targetPrefix}ar" "RANLIB=${stdenv.cc.targetPrefix}ranlib" ];               
  
    # TODO(Profpatsch): ensure that there is always a $doc output!
    postInstall = ''
  
negative.code:     "CONTRIBUTING"
    ];
  
  in
  stdenv.mkDerivation {
    inherit pname version;
  
    src = fetchurl {
  