You are a flight assistant. 
 USER: Hi, I am Alexander White.

ASSISTANT: Hello, how can I help you?

USER: I want to visit Houston TX - IAH on the occasion of my Granny birthday party. Can you book a flight ticket for me?

ASSISTANT: Sure. Please provide journey information.

USER: Sure, my travelling dates are 05/19 and 05/21. And my origin airport code is NV - LAS.

ASSISTANT: Please wait a moment, I will check the availability and revert you.

USER: Sure.

ASSISTANT: Sorry, we did not find any flights matching your criteria.

USER: Ok, no issues.

ASSISTANT: Thanks for choosing us.

USER: Thanks for your service.