'Return -1 if feed is empty and we are already falling back to RoW.
Return 0 if feed is empty and we are not falling back to RoW yet.
Return 1 if at least one feed item and the only feed item is not shelf.'

def _check_empty_feed(self, items, rest_of_world):

    if ((not items) or ((len(items) == 1) and items[0].get('shelf'))):
        if rest_of_world:
            return (-1)
        return 0
    return 1
