[{'role': 'USR', 'utterance': 'So, to start with, I want to talk about a very successful invention, the bicycle. Why? Do you know what the main advantages of bikes are?'}
 {'role': 'SYS', 'utterance': "They don't cost much?"}
 {'role': 'USR', 'utterance': "Yes, and they're not complicated."}
 {'role': 'SYS', 'utterance': "They're easy to use. Yeah?"}
 {'role': 'USR', 'utterance': "Not easy when you're going uphill. Let's say simple."}]
{'role': 'SYS', 'utterance': "OK. Yeah. They're cheap to run. They don't often breakdown. They're safe."}