anchor.diff:     preshed
      numpy
      murmurhash
  -   pytest
  -   hypothesis
      tqdm
      cytoolz
      plac
      six
  -   mock
  -   termcolor
      wrapt
      dill
     ] ++ lib.optional (pythonOlder "3.4") pathlib;
   
   
     checkInputs = [
  +    hypothesis
  +    mock
       pytest
     ];
   
  
positive.code:     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 "wheel>=0.32.0,<0.33.0" "wheel>=0.31.0"
    '';
  
    # Cannot find cython modules.
  
negative.code: , plac
  , six
  , mock
  , wrapt
  , dill
  }:
  
  buildPythonPackage rec {
    pname = "thinc";
    version = "6.12.1";
  
    src = fetchPypi {
      inherit pname version;
      sha256 = "1kkp8b3xcs3yn3ia5sxrh086c9xv27s2khdxd17abdypxxa99ich";
    };
  
    buildInputs = lib.optionals stdenv.isDarwin (with darwin.apple_sdk.frameworks; [
  