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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, values=None, instance_values=None):
 """ Registers a model with this group. :param values: A list of values that should be incremented \ whenever invalidate_cache is called for a instance or class \ of this type. :param instance_values: A list of attribute names that will \ be looked up on the instance of this model that is passed to \ invalidate_cache. The value resulting from that lookup \ will then be incremented. """


        if model in self._models:
            raise Exception("%s is already registered" % model)

        self._models[model] = CacheConfig(values, instance_values)