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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 register(self, model_or_iterable, moderation_class):
 """ Register a model or a list of models for comment moderation, using a particular moderation class. Raise ``AlreadyModerated`` if any of the models are already registered. """

        if isinstance(model_or_iterable, ModelBase):
            model_or_iterable = [model_or_iterable]
        for model in model_or_iterable:
            if model in self._registry:
                raise AlreadyModerated(
                    "The model '%s' is already being moderated" % model._meta.verbose_name
                )
            self._registry[model] = moderation_class(model)