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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 post_save_moderation(self, sender, comment, request, **kwargs):
 """ Apply any necessary post-save moderation steps to new comments. """

        model = comment.content_type.model_class()
        if model not in self._registry:
            return
        self._registry[model].email(comment, comment.content_object, request)