anchor.diff:  { stdenv, fetchurl, substituteAll
   , pkgconfig
  +, makeWrapper
   , cups, zlib, libjpeg, libusb1, pythonPackages, sane-backends, dbus, usbutils
  -, net_snmp, openssl, polkit
  +, net_snmp, openssl, polkit, nettools
   , bash, coreutils, utillinux
   , qtSupport ? true
   , withPlugin ? false
  
positive.code:     sha256 = "1y3wdax2wb6kdd8bi40wl7v9s8ffyjz95bz42sjcpzzddmlhcaxg";
    };
  
    hplipState =
      substituteAll
        {
          inherit version;
          src = ./hplip.state;
        };
  
    hplipPlatforms =
      {
        "i686-linux"   = "x86_32";
        "x86_64-linux" = "x86_64";
        "armv6l-linux" = "arm32";
        "armv7l-linux" = "arm32";
      };
  
    hplipArch = hplipPlatforms."${stdenv.system}"
      or (throw "HPLIP not supported on ${stdenv.system}");
  
negative.code: 
    nativeBuildInputs = [
      pkgconfig
      makeWrapper
    ];
  
    propagatedBuildInputs = with pythonPackages; [
  