The pre-trained model you are loading is a cased model but you have not set `do_lower_case` to False. We are setting `do_lower_case=False` for you but you may want to check this behavior.
Decoding strategy sequential, argmax at each step
Iteration 0: this is a sentence .
	BERT prediction: . is a . .
Iteration 1: . is a sentence .
	BERT prediction: . is a . .
Iteration 2: . is a sentence .
	BERT prediction: . is a . .
Iteration 3: . is a sentence .
	BERT prediction: . is a . .
Iteration 4: . is a . .
	BERT prediction: . . a . .
Final: . is a . .

---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-23-776125cadf25> in <module>()
     18                           cuda=True)
     19     out_file = "data/%s-len%d-burnin%d-topk%d-temp%.3f.txt" % (model_version, max_len, burnin, top_k, temp)
---> 20     write_sents(out_file, bert_sents, should_detokenize=True)

<ipython-input-19-027cb8b83cc4> in write_sents(out_file, sents, should_detokenize)
     15     with open(out_file, "w") as out_fh:
     16         for sent in sents:
---> 17             sent = detokenize(sent[1:-1]) if should_detokenize else sent
     18             out_fh.write("%s\n" % " ".join(sent))

<ipython-input-16-beace4564740> in detokenize(sent)
     20     for i, tok in enumerate(sent):
     21         if tok.startswith("##"):
---> 22             new_sent[len(new_sent) - 1] = new_sent[len(new_sent) - 1] + tok[2:]
     23         else:
     24             new_sent.append(tok)

IndexError: list index out of range

$ head -n3 bert-base-uncased-len40-burnin250-topk100-temp1.000.txt 
sammy harves [ " baby candy " / " dream of baby candy " ( gas station theme ) ) mary ford and baby candy . ( gas station theme ) concept album , featuring mary ford .
3 . contemporary art review ( 2nd ed . october 2008 ) , review with essays on contemporary art , ( london : bateman & partners , february 2009 ) sculpture and the minimalist movement , part .
the truth outside ( matthew greengrass ) psycho ( 1964 ? ) psycho ( orson welles ) monster show ( orson welles ) ( barnacles ) part 3 ( the snare drum ) - narration ;