anchor.diff: -{ buildPythonPackage
  +{ lib
  +, buildPythonPackage
   , fetchPypi
  +, packaging
  +, pluggy
   , py
  +, six
   , virtualenv
  -, pluggy
   , setuptools_scm
  -, six
   }:
   
   buildPythonPackage rec {
  
positive.code:     inherit pname version;
      sha256 = "9f0cbcc36e08c2c4ae90d02d3d1f9a62231f974bcbc1df85e8045946d8261059";
    };
  }
negative.code:   version = "3.1.2";
  
    buildInputs = [ setuptools_scm ];
    propagatedBuildInputs = [ packaging pluggy py six virtualenv ];
  
    doCheck = false;
  
  