def grid_options(grid='fortney'):
    """Function to show available grid options

    PandExo now supports various grid options. Currently, the only one that is availalbe
    is the Fortney grid for giant planets. We will be implementing others, as they
    become available. It will become increasingly difficult for users to see what
    options are availalbe to them. This function should guide users to choose
    the grid that best fits their needs.

    Parameters
    ----------
    grid : str
        (Optional) string which 'fortney'

    """
    return
