def lookups(self, request, model_admin):
        def first_two(s):
            s = unicode(s)
            if len(s) < 2:
                return s
            else:
                return s[:2]

        prefixes = [first_two(alias.name)
                    for alias in model_admin.model.objects.only('name')]

        prefixes = sorted(set(prefixes))

        return [(prefix, prefix) for prefix in prefixes]