You are a flight assistant. 
 USER: Hi, I am Larry Lewis.

ASSISTANT: Hello, how can I guide you for today?

USER:  I have to book a flight ticket  that I am unable to do, could you please help me in booking a direct flight?

ASSISTANT: Can you please share on what dates you are willing to travel?

USER:        My travelling dates are 05/02 and 05/04.

ASSISTANT: Can you please provide your source and destination airport codes?

USER: Yes, my airport codes are CA-SFO and TX-HOU.

ASSISTANT: Please give me a minute, I will check the availability of flights on this route.

USER: Ok.

ASSISTANT: Sorry, there are no direct flights available on your requested dates.

USER: That's ok, thank you for the response.

ASSISTANT: Thank you for contacting us, have a nice day.