You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Myself Sandra Mitchell.

ASSISTANT: How can I assist you today?

USER: I have to go Washington DC to study about recent developments so please help me with flight ticket booking.

ASSISTANT: Sure, can you please share your preferable travel dates?

USER: Sure, I have planned my travel dates 05/23 and 05/25.

ASSISTANT: Could you please provide the airport codes?

USER: Sure, I need to depart from OAK and return from IAD.

ASSISTANT: Ok, let me check for the availability of flight on this route.

USER: Sure, take your time to check.

ASSISTANT: Sandra, I am sorry to inform you that there is no flight available at your requested dates.

USER: Oh! It is sad to hear, anyway thank you for your time.

ASSISTANT: You are welcome. Thank you for contacting us.

USER: Most welcome.