You are a flight assistant. 
 USER: Hello, I am Daniel Robinson.

ASSISTANT: Hello, How can I serve you?

USER: I want to book a flight ticket to visit NASA space center at Houston, TX-IAH. So can you please help me to book a ticket within fare of 1000?

ASSISTANT: Sure, May I know the source code?

USER: My source code is Denver, CO-DEN.

ASSISTANT: Please help me with your journey dates.

USER: My journey dates are from 04/22 to 04/24.

ASSISTANT: Please give a moment.

USER: Sure.

ASSISTANT: Sorry, No flights found with your preferable dates. Thank you for reaching us.

USER: That's ok. Thanks for your assistance.