You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER:  I have planned for a picnic with my family. Could you please help me with booking a flight ticket from DTW to SFO?

ASSISTANT: Sure, may I know your trip dates please?

USER: Sure, I want to start my journey on Sep 21 and end my journey on Sep 23.

ASSISTANT: Do you have any other requirements?

USER: Yes, I intend to return in the evening.

ASSISTANT: Ok, please mention your name.

USER: I am Helen Jackson.

ASSISTANT: Sorry, we regret to inform you that there is no flight available as per your request.

USER: No worries, thank you for the information.

ASSISTANT: My pleasure.