def METHOD_NAME(request: pytest.FixtureRequest, log_file: IO[str]) -> str:
    """
    Starts a jupyter notebook server at the beginning of a session, and
    closes at the end of a session.
    Adds custom.js that runs all the cells on notebook opening. Cleans out
    this custom.js at the end of the test run.
    Returns the url that the jupyter notebook is running at.
    """
    # First - set-up the notebooks to run all cells when they're opened
    #
    # Can be cleaned up further to remember the user's existing customJS
    # and then restore it after the test run.
    from jupyter_core import paths
    config_dir = paths.jupyter_config_dir()
    body = """