anchor.diff:    programs.bash.enableCompletion = true;
     # programs.mtr.enable = true;
     # programs.gnupg.agent = { enable = true; enableSSHSupport = true; };
  -  # programs.qt5ct.enable = true;
   
     # Open ports in the firewall.
     # networking.firewall.allowedTCPPorts = [ ... ];
  
positive.code:   sound.enable = true;
    hardware.pulseaudio.enable = true;
  
    environment.variables.QT_QPA_PLATFORMTHEME = "qt5ct";
  
    services = {
  
      udev.packages = [ pkgs.yubikey-personalization ];
  
negative.code:     yubikey-personalization
      yubikey-personalization-gui
      gnome3.geary
      breeze-icons
      audacity
  
  