anchor.diff:      pytestCheckHook
     ];
   
  -  # Don't run tests for Python 2.7 or Darwin
  -  # Nearly 50% of the test suite requires local network access
  -  # which isn't allowed on sandboxed Darwin builds
  -  doCheck = !(isPy27 || stdenv.isDarwin);
     pytestFlagsArray = [ "--ignore python2" ];
  -  pythonImportsCheck = [ "httplib2" ];
  +
  +  __darwinAllowLocalNetworking = true;
   
     meta = with lib; {
       description = "A comprehensive HTTP client library";
  
positive.code: 
    propagatedBuildInputs = [ pyparsing ];
  
    checkInputs = [
      mock
      pytest-forked
  
negative.code: { lib
  , buildPythonPackage
  , fetchFromGitHub
  , isPy27
  