You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is Lisa Lewis.

ASSISTANT: How can I assist you today?

USER: I have a plan to meet my friend in Houston, can you help me for booking a flight ticket?

ASSISTANT: Sure, I will help you in booking. Can you please share your trip dates?

USER: My travelling dates are from 12/26 till 12/28.

ASSISTANT: Ok, may I know your airport cods?

USER: My travelling airport codes are from DFW to IAH.

ASSISTANT: Please hold on for a while. Sorry, no flights are available on your route.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, have a nice day.