You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am David Taylor. I want to book a flight from BOS and LAX. Can you book it for me?

ASSISTANT: Can you please tell your travelling dates?

USER: My travel date is 07/20 and the return is 07/22.

ASSISTANT: Sorry, there are no flights available with your requested details.

USER: That's ok, no problem. I will next time try with new dates. Thank you.

ASSISTANT: Thank you and have a nice day.