anchor.diff:        
     name = "xaos-" + version;
     meta = {
  +    homepage = http://xaos.sourceforge.net/;
       description = "XaoS - fractal viewer";
  +    license = "GPLv2+";
     };
   }
  
positive.code: let 
    fetchurl = a.fetchurl;
  
    version = a.lib.attrByPath ["version"] "3.4" a; 
    buildInputs = with a; [
      aalib gsl libpng libX11 xproto libXext xextproto 
      libXt zlib gettext intltool perl
  
negative.code: in
  rec {
    src = fetchurl {
      url = "mirror://sourceforge/xaos/xaos-${version}.tar.gz";
      sha256 = "0hj8sxya4s9rc1m4xvxj00jgiczi3ljf2zvrhx34r3ja2m9af7s7";
    };
  
    inherit buildInputs;
  