ERROR while pulling python execute.py

[pumpkinband]

Mode : train

Preparing data in working_dir/
Creating vocabulary working_dir/vocab20000.dec from data/train.dec
processing line 100000

Full Vocabulary Size : 44199

Vocab Truncated to: 20000
Traceback (most recent call last):
File "execute.py", line 319, in
train()
File "execute.py", line 127, in train
enc_train, dec_train, enc_dev, dec_dev, _, _ = data_utils.prepare_custom_data(gConfig['working_directory'],gConfig['train_enc'],gConfig['train_dec'],gConfig['test_enc'],gConfig['test_dec'],gConfig['enc_vocab_size'],gConfig['dec_vocab_size'])
File "/home/samir/tensorflow_chatbot/data_utils.py", line 136, in prepare_custom_data
create_vocabulary(dec_vocab_path, train_dec, dec_vocabulary_size, tokenizer)
File "/home/samir/tensorflow_chatbot/data_utils.py", line 85, in create_vocabulary
vocab_file.write(w + '\n')
TypeError: write() argument 1 must be unicode, not str