anchor.diff:    # Function to remove the first character of a string.
     dropFirstChar = str: concatStrings (tail (stringToCharacters str));
   
  -  _pkgs = pkgs // {fetchUrlWithHeaders = pkgs.callPackage ./pyFetchurl {};};
  +  fetchUrlWithHeaders = pkgs.callPackage ./pyFetchurl.nix {};
  +
  +  fetchPrivateNpm = {sha1, namespace, name, version, bearer}:
  +    fetchUrlWithHeaders {
  +      inherit sha1;
  +      url = "http://registry.npmjs.org/@${namespace}/${name}/-/${name}-${version}.tgz";
  +      headers.Authentication = "Bearer ${bearer}";
  +    };
   in
   
   rec {
  -  pkgs = _pkgs;
  -
     nodejs = pkgs."nodejs-${replaceDots "_" nodejsVersion}" or (
       throw "The given nodejs version ${nodejsVersion} has not been defined."
     );
  
positive.code:         in deriv;
  
        callPackage = callPackageWith {
          inherit pkgs nodePackages buildNodePackage brokenPackage;
        };
        nodePackages = joinSets (map (e: e.nodePackages) extensions) //
  
negative.code:     isNsDir = name: type: type == "directory" && hasPrefix "@" name;
      # Names of NPM packages defined in this directory.
      namespaceDirs = lsFilter isNsDir (/. + rootPath);
      in
      # For each namespace directory, each package folder in it, and
      # each .nix file in that, create a package from that and then
  