You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Hernandez.

ASSISTANT: How may I assist you?

USER: Can you help me to book a flight ticket from TX - IAH to TX - HOU?

ASSISTANT: May I know your travel dates?

USER: Ok, my travel dates are 06/25 and 06/27 respectively.

ASSISTANT: There is no flight on your details.

USER: Ok, not a proble. Thank you for assisting me.

ASSISTANT: Thank you so much.