You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Larry Lopez.

ASSISTANT: How may I assist you today?

USER: I am planning to visit Dallas, can you please book me a ticket from DCA to DFW?

ASSISTANT: May I know your travel dates to search available flight?

USER: My preferable journey dates are from 09/09 to 09/11.

ASSISTANT: Sorry, I could not find any flight with your travel dates.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you for providing information.

ASSISTANT: My pleasure.