You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Brandon Brown. Can you help me to book a flight from DTW on 08/20?

ASSISTANT: I will help you with that. Sure, I am here to help you. Could you please share your travelling dates to search a flight?

USER: I would like to return on 08/22 from PHL.

ASSISTANT: May I know your airport codes?

USER: My airport codes are DTW and PHL.

ASSISTANT: Please wait for a minute.

USER: Ok.

ASSISTANT: I am sorry to say that there is no flight found.

USER: Ok, no issues.

ASSISTANT: Thank you for contacting us.

USER: Thank you.