anchor.diff:    };
   
     environment.systemPackages = with pkgs; [
  -    atom
  +    ( lib.overrideDerivation atom (attrs: {
  +      name = "atom-1.6.2";
  +      src = fetchurl {
  +        url = "https://github.com/atom/atom/releases/download/v1.6.2/atom-amd64.deb";
  +        sha256 = "1kl2pc0smacn4lgk5wwlaiw03rm8b0763vaisgp843p35zzsbc9n";
  +        name = "atom-1.6.2.deb";
  +      };
  +    }))
       binutils
       emacs
       gitFull
  
positive.code:     gc = {
        automatic = true;
        dates = "10:00";
        options = "--delete-older-than 14";
      };
  
      trustedBinaryCaches = [ https://cache.nixos.org https://hydra.nixos.org ];
  
negative.code:     binaryCaches = [ https://cache.nixos.org https://hydra.nixos.org ];
      binaryCachePublicKeys = [ "hydra.nixos.org-1:CNHJZBh9K4tP3EKF6FkkgeVYsS3ohTl+oS0Qa8bezVs=" ];
  
      buildCores = 0;
  
      extraOptions = ''
        auto-optimise-store = true
      '';
  