import shutil missing

[Chop1]

2020-04-21 15:10:25.662351: Start training...
2020-04-21 15:10:25.662382: Setting up Saver...
Traceback (most recent call last):
  File "main.py", line 83, in <module>
    main(args)
  File "main.py", line 75, in main
    model.train()
  File "....../model.py", line 579, in train
    shutil.rmtree(self.log_dir)
NameError: name 'shutil' is not defined

model.py is missing import shutil