You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you today?

USER: Can you please help me to book a flight from IAD to PHL?

ASSISTANT: Sure, may I know your travel dates?

USER: Sure, I want to travel on Feb 1 and need to return on Feb 3.

ASSISTANT: Do you have any specifications?

USER: I am looking for a flight with single connection.

ASSISTANT: Please share me your name.

USER: Mary Turner here.

ASSISTANT: Sorry, there is no flight at this moment.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you.