anchor.diff:     cytoolz
      plac
      six
  +   srsly
      wrapt
      dill
  +   wasabi
     ] ++ lib.optional (pythonOlder "3.4") pathlib;
   
   
  
positive.code: 
    prePatch = ''
      substituteInPlace setup.py \
        --replace "pathlib==1.0.1" "pathlib>=1.0.0,<2.0.0" \
        --replace "plac>=0.9.6,<1.0.0" "plac>=0.9.6" \
        --replace "msgpack-numpy<0.4.4" "msgpack-numpy" \
        --replace "wheel>=0.32.0,<0.33.0" "wheel" \
        --replace "wrapt>=1.10.0,<1.11.0" "wrapt" \
        --replace "msgpack>=0.5.6,<0.6.0" "msgpack"
    '';
  
    # Cannot find cython modules.
  
negative.code: , mock
  , wrapt
  , dill
  , blis
  , srsly
  , wasabi
  }:
  
  buildPythonPackage rec {
    pname = "thinc";
    version = "7.0.4";
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "14v8ygjrkj63dwd4pi490ld6i2d8n8wzcf15hnacjjfwij93pa1q";
    };
  
    buildInputs = lib.optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
  