anchor.diff:    };
   
     libarcusLulzbot = callPackage ./libarcus.nix {
  -    inherit (python3Packages) buildPythonPackage sip pythonOlder;
  +    inherit (python3.pkgs) buildPythonPackage sip pythonOlder;
     };
     libsavitarLulzbot = callPackage ./libsavitar.nix {
  -    inherit (python3Packages) buildPythonPackage sip pythonOlder;
  +    inherit (python3.pkgs) buildPythonPackage sip pythonOlder;
     };
   
  -  inherit (python3Packages) buildPythonPackage pyqt5 numpy scipy shapely pythonOlder;
  +  inherit (python3.pkgs) buildPythonPackage pyqt5 numpy scipy shapely pythonOlder;
     curaengine = callPackage ./curaengine.nix {
       inherit libarcusLulzbot;
     };
     uraniumLulzbot = callPackage ./uranium.nix {
       inherit callPackage libarcusLulzbot;
  -    inherit (python3Packages) buildPythonPackage pyqt5 numpy scipy shapely pythonOlder;
  +    inherit (python3.pkgs) buildPythonPackage pyqt5 numpy scipy shapely pythonOlder;
     };
   in
  -python3Packages.buildPythonApplication rec {
  -  name = "cura-lulzbot-${version}";
  +mkDerivation rec {
  +  pname = "cura-lulzbot";
     version = "3.6.20";
   
     src = fetchgit {
  
positive.code:     EOF
    '';
  
    meta = with lib; {
      description = "3D printer / slicing GUI built on top of the Uranium framework";
      homepage = https://code.alephobjects.com/diffusion/CURA/;
  
negative.code: { lib, mkDerivation, wrapQtAppsHook, callPackage, fetchgit, cmake, jq, python3, qtbase, qtquickcontrols2 }:
  
  let
    # admittedly, we're using (printer firmware) blobs when we could compile them ourselves.
  