def pytest_sessionstart(session: Session) -> None:
    """Called after the ``Session`` object has been created and before performing collection
    and entering the run test loop.

    :param session: The pytest session object.

    Use in conftest plugins
    =======================

    This hook is only called for :ref:`initial conftests <pluginorder>`.
    """
Called after the ``Session`` object has been created and before performing collection
    and entering the run test loop.

    :param session: The pytest session object.

    Use in conftest plugins
    =======================

    This hook is only called for :ref:`initial conftests <pluginorder>`.
    
src/_pytest/hookspec.py