anchor.diff:    
     environment.systemPackages = with pkgs; [
       xpdf
  -    #nixops
  -    nixbang
  -    packer
       firefox
       awscli
       #keybase-node-client
  
positive.code:     gnumake
      python27Packages.pip
      pypy
      linuxPackages_3_4.virtualbox
      mtr
      xclip
      terminus_font
  
negative.code:     scrot
      silver-searcher
      terminator
      xdg_utils
      xlibs.xev
      xlibs.xset
    ];
  
    nixpkgs.config = {
  
  