anchor.diff:    ] ++ lib.optional (pythonOlder "3.3") ipaddress;
   
     postPatch = ''
  -    find tests -type d -name "__pycache__" | xargs rm -r
       substituteInPlace setup.py --replace "pytest>=3.8.0,<3.9" "pytest"
  +
  +    # see https://github.com/joke2k/faker/pull/911, fine since we pin correct
  +    # versions for python2
  +    substituteInPlace setup.py --replace "more-itertools<6.0.0" "more-itertools"
     '';
   
     meta = with lib; {
  
positive.code:   buildInputs = [ pytestrunner ];
    checkInputs = [
      email_validator
      mock
      ukpostcodeparser
      pytest
    ];
  
    propagatedBuildInputs = [
  
negative.code: { lib, buildPythonPackage, fetchPypi, pythonOlder,
    # Build inputs
    dateutil, six, text-unidecode, ipaddress ? null
    # Test inputs
    , email_validator
    , freezegun
    , mock
    , more-itertools
    , pytest
    , pytestrunner
    , random2
    , ukpostcodeparser
  }:
  
  assert pythonOlder "3.3" -> ipaddress != null;
  
  