anchor.diff:        []
       else
         let
  -        x = pkgs.lib.head list;
  -        xs = pkgs.lib.filter (p: f x != f p) (pkgs.lib.drop 1 list);
  +        x = lib.head list;
  +        xs = lib.filter (p: f x != f p) (lib.drop 1 list);
         in
           [x] ++ nubOn f xs;
   
  -  pkgs = import ./../../default.nix (if include-overlays then { } else { overlays = []; });
  -
     packagesWith = cond: return: set:
       nubOn (pkg: pkg.updateScript)
  -      (pkgs.lib.flatten
  -        (pkgs.lib.mapAttrsToList
  +      (lib.flatten
  +        (lib.mapAttrsToList
             (name: pkg:
               let
                 result = builtins.tryEval (
  -                if pkgs.lib.isDerivation pkg && cond name pkg
  +                if lib.isDerivation pkg && cond name pkg
                     then [(return name pkg)]
                   else if pkg.recurseForDerivations or false || pkg.recurseForRelease or false
                     then packagesWith cond return pkg
  
positive.code: 
    packageByName = name:
      let
          package = pkgs.lib.attrByPath (pkgs.lib.splitString "." name) null pkgs;
      in
        if package == null then
          builtins.throw "Package with an attribute name `${name}` does not exists."
  
negative.code:   packagesWithUpdateScriptAndMaintainer = maintainer':
      let
        maintainer =
          if ! builtins.hasAttr maintainer' lib.maintainers then
            builtins.throw "Maintainer with name `${maintainer'} does not exist in `maintainers/maintainer-list.nix`."
          else
            builtins.getAttr maintainer' lib.maintainers;
      in
        packagesWith (name: pkg: builtins.hasAttr "updateScript" pkg &&
                                   (if builtins.hasAttr "maintainers" pkg.meta
  