运行识别验证码时报错

[fizzday]

$ py captcha_cnn.py 
Traceback (most recent call last):
  File "captcha_cnn.py", line 32, in <module>
    pre_text = captcha2text([image])
  File "captcha_cnn.py", line 21, in captcha2text
    saver.restore(sess, tf.train.latest_checkpoint('.'))
  File "/Users/fizz/venv/lib/python3.6/site-packages/tensorflow/python/training/saver.py", line 1751, in restore
    raise ValueError("Can't load save_path when it is None.")
ValueError: Can't load save_path when it is None.