anchor.diff:    # List packages installed in system profile. To search, run:
     # $ nix search wget
     # environment.systemPackages = with pkgs; [
  -  #   wget vim
  +  #   vim # Do not forget to add an editor to edit configuration.nix! The Nano editor is also installed by default.
  +  #   wget
  +  #   firefox
     # ];
   
     # Some programs need SUID wrappers, can be configured further or are
  
positive.code:   # programs.gnupg.agent = {
    #   enable = true;
    #   enableSSHSupport = true;
    #   pinentryFlavor = "gnome3";
    # };
  
    # List services that you want to enable:
  
negative.code:   # this value at the release version of the first install of this system.
    # Before changing this value read the documentation for this option
    # (e.g. man configuration.nix or on https://nixos.org/nixos/options.html).
    system.stateVersion = "21.11"; # Did you read the comment?
  
  }
  