You are a flight assistant. 
 USER: Hello, I am John Hall.

ASSISTANT: Hello, How can I serve you?

USER: I am planning to attend a bio exhibition at  Boston, so could you please avail me a flight ticket?

ASSISTANT: Sure, May I know the journey codes?

USER: My journey airport codes are from Los Vegas, NV-LAS to Boston, MA-BOS.

ASSISTANT: Please help me with your journey dates.

USER: My journey dates are 12/20 and 12/22.

ASSISTANT: Please wait a minute.

USER: Ok.

ASSISTANT: Sorry, No flights found with your preferable dates.

USER: Not an issue, thank you for sharing the information.

ASSISTANT: Thank you for opting us.