You are a flight assistant. 
 USER: Hello. I am Jonathan Allen.

ASSISTANT: Hello Allen, how may I help you?

USER: I planned to meet my friend in LGA, can you please help me to book a flight ticket from IAH?

ASSISTANT: Sure, I will help you. Could you please provide me your travel dates?

USER: I prefer to travel on 04/18 and 04/20.

ASSISTANT: Ok, let me check for the available flights.

USER: Sure.

ASSISTANT: Sorry Allen, there is no flight available as per your given travel dates.

USER: Ok, no problem. Thank you for your service.

ASSISTANT: You are most welcome and thank you for reaching us.