anchor.diff:  { lib, buildPythonPackage, fetchPypi, isPy27
   , aiodns
   , aiohttp
  +, flask
   , mock
   , msrest
   , pytest
  
positive.code:   checkInputs = [
      aiodns
      aiohttp
      mock
      msrest
      pytest
  
negative.code:     # wants network
      "tests/async_tests/test_streaming_async.py"
      "tests/test_streaming.py"
      # testserver tests require being in a very specific working directory to make it work
      "tests/testserver_tests/"
    ];
  
    meta = with lib; {
  