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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def edit_link(self, inst):
 """ Edit link for the change view """

        if not inst.is_active:
            return u'--'
        update_url = reverse('admin:{}_{}_add'.format(self.model._meta.app_label, self.model._meta.model_name))
        update_url += "?source={}".format(inst.pk)
        return u'<a href="{}">{}</a>'.format(update_url, _('Update'))