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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 run_model(self, model_run, run_url):
 """Execute the given model run. Throws a ValueError if the given run specifies an unknown model or if the model connector is invalid. An EngineException is thrown if running the model (i.e., communication with the backend) fails. Parameters model_run : ModelRunHandle Handle to model run run_url : string URL for model run information """

        # Get model to verify that it exists and to get connector information
        model = self.get_model(model_run.model_id)
        if model is None:
            raise ValueError('unknown model: ' + model_run.model_id)
        # By now there is only one connector. Use the buffered connector to
        # avoid closed connection exceptions
        RabbitMQConnector(model.connector).run_model(model_run, run_url)