def pytest_report_header(config, startdir):
    """ return a string or list of strings to be displayed as header info for terminal reporting.

    :param _pytest.config.Config config: pytest config object
    :param startdir: py.path object with the starting dir

    .. note::

        This function should be implemented only in plugins or ``conftest.py``
        files situated at the tests root directory due to how pytest
        :ref:`discovers plugins during startup <pluginorder>`.
    """
