{ pkgs }:
 let
   packages = extras:
     (with pkgs; [ dtach nixpkgs-fmt nixfmt glibcLocales ]) ++ extras;
 
   utils = {
     untar = path:
       pkgs.runCommand "untar" { buildInputs = [ pkgs.gnutar ]; } ''
         mkdir -p "$out"
         cd "$out"
         tar --strip-components=1 -xf "${path}"
       '';
   };
 in
 { inherit packages utils; }