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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 create_model(model_folder, model_type, topology, override):
 """ Create a model if it doesn't exist already. Parameters model_folder : The path to the folder where the model is described with an `info.yml` model_type : MLP topology : Something like 160:500:369 - that means the first layer has 160 neurons, the second layer has 500 neurons and the last layer has 369 neurons. override : boolean If a model exists, override it. """

    latest_model = utils.get_latest_in_folder(model_folder, ".json")
    if (latest_model == "") or override:
        logging.info("Create a base model...")
        model_src = os.path.join(model_folder, "model-0.json")
        command = "%s make %s %s > %s" % (utils.get_nntoolkit(),
                                          model_type,
                                          topology,
                                          model_src)
        logging.info(command)
        os.system(command)
    else:
        logging.info("Model file already existed.")