anchor.diff:      py
       setuptools
       six
  -    toml
  +    tomli
       wcwidth
     ] ++ lib.optionals (pythonOlder "3.6") [ pathlib2 ];
   
  
positive.code:     # - files are not needed after tests are finished
      pytestRemoveBytecodePhase () {
          # suffix is defined at:
          #    https://github.com/pytest-dev/pytest/blob/6.2.5/src/_pytest/assertion/rewrite.py#L51-L53
          find $out -name "*-pytest-*.py[co]" -delete
      }
      preDistPhases+=" pytestRemoveBytecodePhase"
  
negative.code: { lib, buildPythonPackage, pythonOlder, fetchPypi, isPy3k, isPyPy
  , atomicwrites
  , attrs
  , hypothesis
  