You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I help you?

USER: My name is Joshua Hill. I want to attend my grandfather memorial service at Houston, TX-HOU. Can you please help me to book a flight ticket?

ASSISTANT: Sure Joshua, could you please provide your source city and travel dates?

USER: Sure, I want to fly out from Washington, DC-DCA on 04/14 and return on 04/16.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: Sorry for the inconvenience, no flights found on your dates.

USER: No problem. thank you.

ASSISTANT: Thanks for approaching us. Have a nice day!.