'Return a list (queryset, really) of all CMS Page objects (in this case)
that are currently using this CMSAttachMenu either directly as a
navigation_extender, or, as part of an apphook.
Calling this DOES perform a DB query.'

@classmethod
def get_instances(cls):

    parent_apps = []
    for app in cls.get_apphooks():
        parent_apps.append(app.__class__.__name__)
    return Page.objects.filter((Q(application_urls__in=parent_apps) | Q(navigation_extenders=cls.__name__)))
