anchor.diff: -{ lib, buildPythonPackage, fetchPypi, pythonOlder,
  -  async_generator, traitlets, nbformat, nest-asyncio, jupyter-client,
  -  pytest, xmltodict, nbconvert, ipywidgets
  +{ lib
  +, buildPythonPackage
  +, fetchPypi
  +, pythonOlder
  +, async_generator
  +, traitlets
  +, nbformat
  +, nest-asyncio
  +, jupyter-client
  +, pytestCheckHook
  +, xmltodict
  +, nbconvert
  +, ipywidgets
   }:
   
  -buildPythonPackage rec {
  +let nbclient = buildPythonPackage rec {
     pname = "nbclient";
     version = "0.6.2";
     format = "setuptools";
  
positive.code:     license = licenses.bsd3;
      maintainers = [ maintainers.erictapen ];
    };
  }
  
negative.code:     hash = "sha256-i0dVPxztB3zXxFN/1dcB1G92gfJLKCdeXMHTR+fJtGs=";
    };
  
    propagatedBuildInputs = [ async_generator traitlets nbformat nest-asyncio jupyter-client ];
  
    # circular dependencies if enabled by default
    doCheck = false;
  
    checkInputs = [ pytestCheckHook xmltodict nbconvert ipywidgets ];
  
    preCheck = ''
      export HOME=$(mktemp -d)
    '';
  
    passthru.tests = {
      check = nbclient.overridePythonAttrs (_: { doCheck = true; });
    };
  
    meta = with lib; {
      homepage = "https://github.com/jupyter/nbclient";
  