anchor.diff:            ++ stdenv.lib.optional (pythonOlder "3.5") typing;
         });
       };
  -  } else python36;
  +  } else python3;
   
   in python.pkgs.buildPythonPackage {
     pname = "gns3-server";
  
positive.code: { stable, branch, version, sha256Hash }:
  
  { stdenv, python36, fetchFromGitHub }:
  
  let
    python = if stable then python36.override {
      packageOverrides = self: super: {
        async-timeout = super.async-timeout.overridePythonAttrs (oldAttrs: rec {
          version = "2.0.1";
  
negative.code:     sha256 = sha256Hash;
    };
  
    postPatch = ''
      # "typing" is only required for Python 3.4 and breaks Python 3.7:
      sed -iE "s/.*typing.*//" requirements.txt
    '';
  
    propagatedBuildInputs = with python.pkgs; [
      aiohttp-cors yarl aiohttp multidict
      jinja2 psutil zipstream raven jsonschema
      (python.pkgs.callPackage ../../../development/python-modules/prompt_toolkit/1.nix {})
    ] ++ stdenv.lib.optional (!stable) python.pkgs.distro;
  
  