anchor.diff:    libxml2 = callPackage ../development/libraries/libxml2 { };
   
     libxml2Python = pkgs.buildEnv { # slightly hacky
  -    name = "libxml2+py-${libxml2.version}";
  +    name = "libxml2+py-${res.libxml2.version}";
       paths = with libxml2; [ dev bin py ];
       inherit (libxml2) passthru;
       # the hook to find catalogs is hidden by buildEnv
  
positive.code:   inherit (callPackages ../data/fonts/tai-languages { }) tai-ahom;
  
    tango-icon-theme = callPackage ../data/icons/tango-icon-theme {
      gtk = gtk2;
    };
  
    themes = name: callPackage (../data/misc/themes + ("/" + name + ".nix")) {};
  
negative.code: 
    fakenes = callPackage ../misc/emulators/fakenes { };
  
    faust = res.faust2;
  
    faust1 = callPackage ../applications/audio/faust/faust1.nix { };
  
  