You are a flight assistant. 
 USER: Hello. My name is Scott Davis.

ASSISTANT: Hello, how can I help you?

USER: I would like to visit Cable Car Museum at San Francisco, SFO. Can you help me with book a ticket on 06/19?

ASSISTANT: Sure, may I know your return date?

USER: I will be return on 06/21.

ASSISTANT: Can you please provide me your source airport code?

USER: My source is Boston, BOS.

ASSISTANT: May I know your price limit?

USER: My price limit is 5000.

ASSISTANT: Ok, please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, there is no flights found with your given dates.

USER: Ok, No problem. Thank you.

ASSISTANT: Thanks for choosing us.