You are a flight assistant. 
 USER: Hi, I am Samuel Thomas.

ASSISTANT: Hello Thomas, how can I assist you?

USER: I would like to travel from IAH to DEN, could you help me in booking a flight ticket?

ASSISTANT: Sure. Can you please provide on which dates you need booking?

USER: Sure, my preferable journey dates are 07/25 and returning on 07/27.

ASSISTANT: Sorry to say there are no flights available as per your request.

USER: OK, thank you for your information.

ASSISTANT: Thank you.