KeyError: 'UNK'

[doudoubean]

When I run your project ,this error occurs. How to solve this problem?

Traceback (most recent call last):
File "correct_text.py", line 438, in
tf.app.run()
File "/usr/local/lib/python3.5/dist-packages/tensorflow/python/platform/app.py", line 43, in run
sys.exit(main(sys.argv[:1] + flags_passthrough))
File "correct_text.py", line 413, in main
data_reader = MovieDialogReader(config, FLAGS.train_path)
File "/opt/yangzhanku/correct_text/deep-text-corrector-master/text_corrector_data_readers.py", line 88, in init
self.UNKNOWN_ID = self.token_to_id[MovieDialogReader.UNKNOWN_TOKEN]
KeyError: 'UNK'