def normalize_together(option_together):
    """
    option_together can be either a tuple of tuples, or a single
    tuple of two strings. Normalize it to a tuple of tuples, so that
    calling code can uniformly expect that.
    """
    try:
        if not option_together:
            return ()
        if not isinstance(option_together, (tuple, list)):
            raise TypeError
        first_element = option_together[0]
        if not isinstance(first_element, (tuple, list)):
            option_together = (option_together,)
        # Normalize everything to tuples
        return tuple(tuple(ot) for ot in option_together)
    except TypeError:
        # If the value of option_together isn't valid, return it
        # verbatim; this will be picked up by the check framework later.
        return option_together