def label_from_instance(self, obj):
        """
        Creates labels which represent the tree level of each node when
        generating option labels.
        """
        level = getattr(obj, obj._mptt_meta.level_attr)
        level_indicator = mark_safe(conditional_escape(self.level_indicator) * level)
        return mark_safe(u'%s %s' % (level_indicator, conditional_escape(smart_unicode(obj))))
Creates labels which represent the tree level of each node when
        generating option labels.