anchor.diff:    nixpkgs.config = {
       allowUnfree = true;
     };
  +
     environment.systemPackages = (with pkgs; [
  -    rsync openssh git neovim gnupg smartmontools qemu
  -    nmap tcpdump dnsutils
  +    rsync openssh git pijul neovim gnupg smartmontools qemu
  +    nmap tcpdump dnsutils traceroute
       file htop tree hexd pixd xsel maim xdotool rlwrap
       latinmodern-math lmodern gummi texlive.combined.scheme-full
       signal-desktop quasselClient
       gimp darktable krita 
       zeal mpv firefox
  -    mathematica
  +    mathematica jupyter
       python3 ghc jq dash nodejs racket
  -    virtualbox arduino
  -    nix-index
  +    virtualbox # arduino
  +    nix-index # plover.dev
  +    gnuradio gqrx gnuradio-osmosdr gqrx rtl-sdr
     ]) ++ (with pkgs.gnome3; [
       gnome-terminal gnome-disk-utility
       gnome-logs gnome-system-log
  
positive.code: 
    # Printing.
    services.printing.enable = true;
    services.printing.drivers = with pkgs; [ gutenprint gutenprintBin ];
  
    # My users.
    security.sudo.enable = true;
  
negative.code:     gnome-clocks gnome-weather
    ]);
  
    # RTL-SDR
    services.udev.packages = [ pkgs.rtl-sdr ];
  
    # Package comfort.
    nixpkgs.config.packageOverrides = pkgs: with pkgs; {
      neovim = neovim.override {
  