def METHOD_NAME(model_args, results_df):
    """Chooses which model to use in StatsForecast.
    If the user passes 'auto' for their model_name, this will choose the best
    model based on in-sample cross validation performance. This will then modify
    the model_args dictionnary, replacing 'auto' with the best-performing model.
    """
    if model_args["model_name"] == "auto":
        model_args["model_name"] = get_best_model_from_results_df(results_df)
    model_args["season_length"] = get_season_length(model_args["frequency"])
    model = model_dict[model_args["model_name"]]
    return model(season_length=model_args["season_length"])