anchor.diff: -{ stdenv
  +{ lib
   , pkgs
   , buildPythonPackage
   , python
   , fetchPypi
  +, pythonOlder
   , html5lib
   , pytest
  -, cython
   , preshed
   , ftfy
   , numpy
  
positive.code: , dill
  , requests
  , thinc
  , pip
  , regex
  }:
  
  buildPythonPackage rec {
  
negative.code:   '';
  
    propagatedBuildInputs = [
     numpy
     murmurhash
     cymem
     preshed
     thinc
     plac
     six
     html5lib
     ujson
     dill
     requests
     regex
     ftfy
     msgpack-python
     msgpack-numpy
    ] ++ lib.optional (pythonOlder "3.4") pathlib;
  
    checkInputs = [
      pytest
  