[{'role': 'USR', 'utterance': 'Can I help you, sir?'}
 {'role': 'SYS', 'utterance': "I want to find a book called Gone with the Wind. But I can't find it."}
 {'role': 'USR', 'utterance': 'Let me give you a hand. The author is. . .'}
 {'role': 'SYS', 'utterance': 'Margaret Mitchell.'}
 {'role': 'USR', 'utterance': 'Oh, yes. Here it is.'}
 {'role': 'SYS', 'utterance': 'Thank you very much. I have been looking for it for a long time. Is this the latest edition?'}
 {'role': 'USR', 'utterance': 'Yes, we have both the paperback and hardcover. which would you want to buy?'}]
{'role': 'SYS', 'utterance': 'How about the price of the hardcover?'}