You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I aid you?

USER: I am Patrick Evans. I need to attend a cultural event in San Francisco so please help me with flight ticket booking from Houston.

ASSISTANT: Sure, may I know on what dates you are willing to travel?

USER: Thank you, I need to travel on dates of 08/11 and 08/13.

ASSISTANT: Can you please share your airport codes?

USER: Sure, I would like to travel from IAH to SFO.

ASSISTANT: Sorry, there are no flights found on your travel dates.

USER: Oh! It is sad to hear. Anyway, thank you for your time.

ASSISTANT: Thank you for choosing us.

USER: Most welcome.