code: def save(self, checkpoint_file):
      if self.model is None:
          raise Exception(
              "Needs to call fit_eval or restore first before calling save"
          )
      with open(checkpoint_file, "wb") as fout:
          pickle.dump(self.model, fout)
  
file_path: analytics-zoo/pyzoo/zoo/chronos/model/arima.py
imports: import os
  import pickle
  from pmdarima.arima import ARIMA
  from pmdarima.arima import ndiffs
  from pmdarima.arima import nsdiffs
  from zoo.orca.automl.metrics import Evaluator
  from zoo.orca.automl.model.abstract import BaseModel, ModelBuilder
label_desc: Use image node_id 6 for calling the ARIMAModel obj's underlying member method code with example usage: obj.save(checkpoint_file) without return types