anchor.diff:      # Theorem provers
       isabelle
       haskellPackages.Agda
  +
  +    # Android development
  +    pkgs-unstable.android-studio
  +    pkgs-unstable.androidenv.platformTools
  +    gradle
   
       # Gnome 3
       gnome3.gnome-tweak-tool
  
positive.code: { config, pkgs, ... }:
  let
    unstable = import <nixos-unstable> { config = { allowUnfree = true; }; };
  in
  
  {
  
negative.code: 
    services = {
  
      udev.packages = [ pkgs.yubikey-personalization pkgs.android-udev-rules ];
  
      # Enable the OpenSSH daemon.
      # openssh.enable = true;
  