anchor.diff:      license = lib.licenses.bsd3;
       maintainers = with lib.maintainers; [ fridh ];
     };
  -}+}
  
positive.code: 
    src = fetchPypi {
      inherit pname version;
      sha256 = "98e8af5edff5d24e4d31e73bc21043130ae9d955a91aa93fc0bc3b1d0f7b5880";
    };
  
    checkInputs = [ ipykernel ipython mock pytest ];
    propagatedBuildInputs = [traitlets jupyter_core pyzmq dateutil tornado ] ++ lib.optional isPyPy py;
  
    checkPhase = ''
      py.test
    '';
  
    # Circular dependency with ipykernel
    doCheck = false;
  
negative.code: , dateutil
  , isPyPy
  , py
  , tornado
  }:
  
  