You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, How can I assist you?

USER: As I am a scientist, I would like to visit the NASA space center, which is located at Houston, TX - IAH. Can you assist me to book a flight ticket having single connection?

ASSISTANT: Sure, Please help me with your travel dates.

USER: My preferable travel dates are on 04/11 and return at 04/13.

ASSISTANT: May I know the source code?

USER: I want to start my journey from DC - IAD.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Ok, not a problem at all.

ASSISTANT: Can I get your name?

USER: I am Jonathan Smith. Thank you for assisting me out.

ASSISTANT: Thank you for availing us.