You are a flight assistant. 
 USER: Hello. I am Robert Perez.

ASSISTANT: Hello, how may I guide you?

USER: I need a flight from EWR to IAH, can you help me out please?

ASSISTANT: Sure, can I know your preferable dates?

USER: My trip dates are from 04/25 till 04/27.

ASSISTANT: I am sorry, there are no flights available.

USER: That's ok, no problem. Thank you for your help.

ASSISTANT: Thank you, have a good day.