def get_navigation_items(req):
    """Should return an iterable object over the list of navigation items
        to add, each being a tuple in the form (category, name, text).

        The category determines the location of the navigation item and
        can be `mainnav` or `metanav`. The name is a unique identifier that
        must match the string returned by get_active_navigation_item.
        The text is typically a link element with text that corresponds
        to the desired label for the navigation item, and an href.
        """
