code: def fallback(self):
      if self.fallback_ is None:
          self.fallback_ = self.fallback_future.result()
          self.fallback_future = None
          self.tpe.shutdown()
      return self.fallback_
  
imports: import os
  from concurrent.futures import ThreadPoolExecutor
  import logging
  import sys
  import re
  import joblib
  import numpy
  import tensorflow
  from tensorflow.compat.v1.train import SessionRunHook
  from tensorflow_estimator.python.estimator.early_stopping import _StopOnPredicateHook
  from finetune.errors import FinetuneError
  from finetune.config import get_config
  from finetune.util.metrics import read_eval_metrics
label_desc: Use image node_id 3 for calling the Saver obj's underlying member method code with example usage: obj.fallback() and returns: self