@classmethod
def unauthorized_pages(cls, user):
    """
        Returns a list of pks of page that user is unauthorized to access
        """
    if user.is_superuser:
        return list()
    groups = user.groups.all()
    if user.is_anonymous() or len(groups) == 0:
        return list(set(cls.objects.values_list('page__pk', flat=True)))
    pages = cls.objects.filter(group__in=groups).values_list('page__pk',
        flat=True)
    return list(cls.objects.exclude(page__in=pages).values_list('page__pk',
        flat=True))
