anchor.diff: -{ lib, buildPythonPackage, fetchPypi, pythonOlder
  +{ lib, buildPythonPackage, fetchPypi
   , attrs
   , bidict
   , bitstruct
  
positive.code:   # No tests
    doCheck = false;
  
    disabled = pythonOlder "3.6";
  
    meta = with lib; {
      homepage = "https://github.com/thebigmunch/audio-metadata";
      description = "A library for reading and, in the future, writing metadata from audio files";
  
negative.code: 
    postPatch = ''
      substituteInPlace setup.py \
        --replace "'attrs>=18.2,<19.4'" "'attrs'"
    '';
  
    propagatedBuildInputs = [
  