You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you?

USER: I would like to return on 04/15 from Seattle after complete my work. Can you help me book a flight ticket from Philadelphia on 04/13?

ASSISTANT: Sure, may I know your airport codes?

USER: They are from PHL to SEA.

ASSISTANT: May I know your name?

USER: Gregory Garcia is my name.

ASSISTANT: Sorry, there is no flight on your requested dates.

USER: That's fine, thank you for the response.

ASSISTANT: Thank you for reaching us.