You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello,can you please tell me how I will be your helping hand at this time?

USER: I want to book a ticket to my friend with the name of Donna Hernandez, as we have a conference at  DCA. And my journey is from 08/13 to 08/15 with price limit of 500.

ASSISTANT: Ok, may I know your source code?

USER: I want the flight with single connection from DFW.

ASSISTANT: Sorry, no flight found on your details.

USER: Ok, no problem. Thank you for your assistance.

ASSISTANT: Thank you.