anchor.diff: -{ lib, stdenv
  +{ lib
  +, stdenv
  +, aiohttp
   , buildPythonPackage
  +, eventlet
   , fetchFromGitHub
  -, aiohttp
  -, eventlet
   , iana-etc
   , libredirect
   , mock
  +, pytestCheckHook
  +, pythonOlder
   , requests
   , six
   , tornado
   , websocket-client
  -, websockets
  -, pytestCheckHook
   }:
   
   buildPythonPackage rec {
     pname = "python-engineio";
  -  version = "4.2.1";
  +  version = "4.3.0";
  +  format = "setuptools";
  +
  +  disabled = pythonOlder "3.6";
   
     src = fetchFromGitHub {
       owner = "miguelgrinberg";
       repo = "python-engineio";
       rev = "v${version}";
  -    sha256 = "sha256-aAoTeQZCtxddVBPwlyv2j4aACMO9p0vQ/ESkkv4E3VE=";
  +    sha256 = "sha256-ohNRtceh0bHBlnGSFUckG5KzoLY8Q1jvpFee7T78Vto=";
     };
   
     checkInputs = [
  
positive.code:     export NIX_REDIRECTS=/etc/protocols=${iana-etc}/etc/protocols:/etc/resolv.conf=$(realpath resolv.conf) \
        LD_PRELOAD=${libredirect}/lib/libredirect.so
    '';
    postCheck = "unset NIX_REDIRECTS LD_PRELOAD";
  
    # somehow effective log level does not change?
    disabledTests = [ "test_logger" ];
    pythonImportsCheck = [ "engineio" ];
  
    meta = with lib; {
      description = "Python based Engine.IO client and server";
  
negative.code:     requests
      tornado
      websocket-client
      pytestCheckHook
    ];
  
  