anchor.diff:  
     pythonImportsCheck = [ "jupyterlab_git" ];
   
  -  meta = with lib; {
  +  meta = with stdenv.lib; {
       description = "Jupyter lab extension for version control with Git.";
       license = with licenses; [ bsd3 ];
       homepage = "https://github.com/jupyterlab/jupyterlab-git";
  
positive.code: 
    propagatedBuildInputs = [ notebook nbdime git ];
  
    checkInputs = [ pytest ];
  
    checkPhase = ''
  
negative.code: { stdenv
  , buildPythonPackage
  , fetchPypi
  , pythonOlder
  