anchor.diff:    environment.systemPackages = with pkgs; [
       # main apps
       emacs 
  -    firefox
  -    chromium
  +    # firefox
  +    # chromium
       notmuch
       gitAndTools.gitAnnex
   
       # X11 apps
  -    xpdf
  -    gv
  -    ghostscript
   
       # terminal apps 
       units
  
positive.code:     vim
      most
      mosh
  
      # gnupg
      gnupg
  
negative.code:     # file viewers
      mpg321
      vorbisTools
  
      # misc
      pavucontrol
  