anchor.diff:      HOME=$TEMPDIR pytest
     '';
   
  -  propagatedBuildInputs = [ setuptools jedi pluggy future python-jsonrpc-server ]
  +  propagatedBuildInputs = [ setuptools jedi pluggy future python-jsonrpc-server flake8 ]
       ++ stdenv.lib.optional (withProvider "autopep8") autopep8
       ++ stdenv.lib.optional (withProvider "mccabe") mccabe
       ++ stdenv.lib.optional (withProvider "pycodestyle") pycodestyle
  
positive.code: { stdenv, buildPythonPackage, fetchFromGitHub, pythonOlder, isPy27
  , backports_functools_lru_cache, configparser, futures, future, jedi, pluggy, python-jsonrpc-server
  , pytest, mock, pytestcov, coverage, setuptools
  , # Allow building a limited set of providers, e.g. ["pycodestyle"].
    providers ? ["*"]
  
negative.code: 
  buildPythonPackage rec {
    pname = "python-language-server";
    version = "0.29.1";
  
    src = fetchFromGitHub {
      owner = "palantir";
      repo = "python-language-server";
      rev = version;
      sha256 = "0hsp0h8vma8z6f0mg311hp59h6hayl7zzxmy295x5fl2l9iiakfv";
    };
  
    # The tests require all the providers, disable otherwise.
  