anchor.diff:  { lib, fetchPypi, isPy27
   , buildPythonPackage
   , traits, apptools, pytestCheckHook
  -, ipykernel, ipython, setuptools
  +, ipython, setuptools
   }:
   
   buildPythonPackage rec {
  
positive.code:     sha256 = "8864c29aa344f7ac26eeb94788798f2d0cc791dcf95c632da8d79ebc580e114c";
    };
  
    propagatedBuildInputs = [ traits apptools setuptools ];
  
    preCheck = ''
  
negative.code:   '';
  
    checkInputs = [
      ipython pytestCheckHook
    ];
  
    meta = with lib; {
  