You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I aid you?

USER: Andrew Baker here. I would like to travel from Houston to Washington on my personal work. Could you please book a ticket for me?

ASSISTANT: Sure, may I know your preferred airport codes?

USER: IAH and IAD are my preferred airport codes.

ASSISTANT: Sure, on which dates you are planned to travel?

USER: I would like to travel on 07/12 and 07/14.

ASSISTANT: Thank you for your information. Sorry, there is no flight is available as per your details.

USER: No issues, thank you for your timely help.

ASSISTANT: It's my pleasure, have a nice day.