anchor.diff:      sha256 = "67e360ac73b12c52058219bb5f8b3ed4105d2636707a36a7cdafb56fe06db7fe";
     };
   
  -  checkInputs = [ pytest_3 mock ];
  +  checkInputs = [ pytest mock ];
   
     propagatedBuildInputs = [ six twisted ];
   
  
positive.code:     py.test -k "not test_sdist"
    '';
  
    # Needs some fixing for 3.7
    doCheck = !isPy37;
  
    meta = with stdenv.lib; {
      description = "Utilities to support code that runs unmodified on Twisted and asyncio.";
  
negative.code: { stdenv, buildPythonPackage, fetchPypi, pytest, mock, six, twisted,isPy37 }:
  
  buildPythonPackage rec {
    pname = "txaio";
  