You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I aid you?

USER: Can you help me to book a flight ticket from DCA to DFW?

ASSISTANT: Sure, may I know the planned travel dates to check for the flight availability?

USER: My travel dates are Apr 10 and Apr 12.

ASSISTANT: Please provide me the specifications.

USER: I would like to return back in the afternoon time  and an economy class flight ticket.

ASSISTANT: May I know the name?

USER: I am William Davis.

ASSISTANT: Sorry, there are no flights are available for your desired intent.

USER: No problem, thank you for the information.

ASSISTANT: Thank you for reaching us.