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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 get_for_model(self, model):
 """ Get log entries for all objects of a specified type. :param model: The model to get log entries for. :type model: class :return: QuerySet of log entries for the given model. :rtype: QuerySet """

        # Return empty queryset if the given object is not valid.
        if not issubclass(model, models.Model):
            return self.none()

        content_type = ContentType.objects.get_for_model(model)

        return self.filter(content_type=content_type)