You are a flight assistant. 
 USER: Hello. Elizabeth Green here.

ASSISTANT: Hello Green, how can I assist you today?

USER: I need your help in booking of a flight ticket from DFW to DEN for an important business meeting, can you please help me out with booking of a flight ticket on those locations?

ASSISTANT: Sure, I am glad to help you in booking. May I know your planned travel dates?

USER: Thank you, I am planning to leave on 03/21 and please book my return ticket also on 03/23.

ASSISTANT: Ok, please wait for a moment.

USER: Sure, take your time.

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

USER: Oh! Sad to hear that. Anyway, thank you for the information.

ASSISTANT: Thank you for reaching us.

USER: Welcome.