anchor.diff:    propagatedBuildInputs = [
       py-cpuinfo
       pytest
  -  ] ++ optionals isPy2 /* <3.4 */ [
  -    statistics
     ];
  -
  -  #doCheck = true;
   
     meta = with lib; {
       description = "py.test fixture for benchmarking code";
  
positive.code: }:
  
  let
    inherit (lib) optionals;
  
    version = "3.1.1";
  in
  buildPythonPackage rec {
  
negative.code: { stdenv
  , buildPythonPackage
  , fetchPyPi
  , lib
  , unzip
  
  