anchor.diff:  { lib
  -, backports-datetime-fromisoformat
   , backports-zoneinfo
   , buildPythonPackage
   , cached-property
  
positive.code:     tzlocal
    ] ++ lib.optionals (pythonOlder "3.9") [
      backports-zoneinfo
    ] ++ lib.optionals (pythonOlder "3.7") [
      backports-datetime-fromisoformat
    ];
  
    checkInputs = [
  
negative.code: 
  buildPythonPackage rec {
    pname = "exchangelib";
    version = "4.7.0";
    format = "setuptools";
  
    disabled = pythonOlder "3.7";
  
    src = fetchFromGitHub {
      owner = "ecederstrand";
      repo = pname;
      rev = "v${version}";
      sha256 = "sha256-APT/esskyigt6u3A+KVTAlmZDMppeyKb9Ws+95hDLcM=";
    };
  
    propagatedBuildInputs = [
  