anchor.diff:  { stdenv
   , buildPythonPackage
   , fetchPyPi
  -, isPy2
   , lib
   , unzip
   
  
positive.code: }:
  
  let
    inherit (lib) optionals;
  
    version = "3.1.1";
  in
  buildPythonPackage rec {
  
negative.code:   propagatedBuildInputs = [
      py-cpuinfo
      pytest
    ];
  
    meta = with lib; {
      description = "py.test fixture for benchmarking code";
  