You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: Can you help me to book a flight to DCA?

ASSISTANT: Yes I will, please share your source code.

USER: Sure, the source code which I planned is LAS.

ASSISTANT: On which dates you want me to confirm your ticket?

USER: My travel dates are 11/10 and 11/12.

ASSISTANT: Please wait for a while I'll be back with your flight details.

USER: Sure, take your time. Please make sure there is a connecting flight.

ASSISTANT: Ok, meanwhile can you help me with your name?

USER: Yes, my name is Nancy Turner.

ASSISTANT: Sorry Nancy, you have no flights on your preferred dates.

USER: That's ok, I will plan my journey some other day. Thank for your assistance.

ASSISTANT: Thank you for choosing our help.