anchor.diff:  
     newScope = extra: lib.callPackageWith (defaultScope // extra);
   
  -  defaultScope = pkgs // pkgs.xorg;
  -
  -
  -  # The package compositions.  Yes, this isn't properly indented.
  -  pkgsFun = __overrides: with helperFunctions; helperFunctions // rec {
  -
  -
  +  
     # Override system. This is useful to build i686 packages on x86_64-linux.
     forceSystem = system: (import ./all-packages.nix) {
       inherit system;
       inherit bootStdenv noSysDirs gccWithCC gccWithProfiling config;
     };
   
  +  
     # Used by wine, firefox with debugging version of Flash, ...
     pkgsi686Linux = forceSystem "i686-linux";
   
     callPackage_i686 = lib.callPackageWith (pkgsi686Linux // pkgsi686Linux.xorg);
  -
  -  inherit __overrides;
   
   
     # For convenience, allow callers to get the path to Nixpkgs.
  
positive.code:   # Allow packages to be overriden globally via the `packageOverrides'
    # configuration option, which must be a function that takes `pkgs'
    # as an argument and returns a set of new or overriden packages.
    # `__overrides' is a magic attribute that causes the attributes in
    # its value to be added to the surrounding `rec'.  The
    # `packageOverrides' function is called with the *original*
    # (un-overriden) set of packages, allowing packageOverrides
    # attributes to refer to the original attributes (e.g. "foo =
    # ... pkgs.foo ...").
    # We don't want stdenv overrides in the case of cross-building, or
    # otherwise the basic overrided packages will not be built with the
    # crossStdenv adapter.
    overrides = (getConfig ["packageOverrides"] (pkgs: {})) pkgsOrig //
      (if pkgsOrig.stdenv ? overrides && crossSystem == null
       then pkgsOrig.stdenv.overrides else { });
  
    pkgsOrig = pkgsFun { }; # the un-overriden packages, passed to packageOverrides
    pkgs = pkgsFun overrides; # the overriden, final packages
  
  
    # We use `callPackage' to be able to omit function arguments that
  
negative.code:     in
        # allow both:
        # { /* the config */ } and
        # { pkgs, ... } : { /* the config */ }
        if builtins.isFunction configExpr
          then configExpr { inherit pkgs; }
          else configExpr;
  
    # Return an attribute from the Nixpkgs configuration file, or
  