You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you today?

USER: Myself Patrick Collins, can you help me to book a flight ticket on the dates 02/20 and 02/22?

ASSISTANT: Ok, can I know your nearest airport source code and target airport code?

USER: Yes as I have a meeting in Washington DC, IAD and origin airport is IAH.

ASSISTANT: Ok, wait for a while.

USER: Ok, please take your own time.

ASSISTANT: Ok, thank you your patience. Sorry Patrick here there is no flight available for your desired dates.

USER: That's ok, my trip can be postponed. Thank you for assisting me.

ASSISTANT: Thank you for reaching us.