anchor.diff:  { lib, buildPythonPackage, fetchFromGitHub, pythonOlder, isPy27
  +, git
   , importlib-metadata
   , intreehooks
   , pathlib2
  
positive.code: 
  buildPythonPackage rec {
    pname = "poetry-core";
    version = "1.0.4";
    format = "pyproject";
  
    src = fetchFromGitHub {
      owner = "python-poetry";
      repo = pname;
      rev = version;
      sha256 = "0jgd4d7m5y8ly8n0l9lcq7cjab2y3hifk90f343ksmjzssfd5lg3";
    };
  
    postPatch = lib.optionalString (pythonOlder "3.8") ''
  
negative.code:   ];
  
    checkInputs = [
      git
      pep517
      pytest-mock
      pytestCheckHook
  