anchor.diff:  
     # Virtualization.
     boot.kernelModules = [ "kvm-intel" ];
  -  virtualisation.virtualbox.host.enable = true;
  +  # virtualisation.virtualbox.host.enable = true;
   
     # ZFS services.
     services.zfs.autoSnapshot.enable = true;
  
positive.code:   };
  
    environment.systemPackages = (with pkgs; [
      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 jupyter
      python3 ghc jq dash nodejs racket
      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
      gnome-power-manager simple-scan
      nautilus file-roller
      eog evince
      baobab gnome-system-monitor gnome-session
      gnome-font-viewer gnome-characters gnome-screenshot
      gnome-clocks gnome-weather
    ]);
  
    # RTL-SDR
    services.udev.packages = [ pkgs.rtl-sdr ];
  
    # Package comfort.
    nixpkgs.config.packageOverrides = pkgs: with pkgs; {
  
negative.code:         [org.gnome.desktop.interface]
          clock-show-seconds=true
    
          [org.gnome.shell.overrides]
          dynamic-workspaces=false
  
          [org.gnome.desktop.wm.preferences]
          num-workspaces=9
  
          [org.gnome.desktop.wm.keybindings]
          move-to-workspace-1=['<Super><Shift>1']
          move-to-workspace-2=['<Super><Shift>2']
  