You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I guide you today?

USER: I am Michael Johnson. I want to book a ticket from IAD to DFW, can you help me?

ASSISTANT: Sure, I will help you with that. Can you please share your preferable journey dates?

USER: My travel dates are June 20 and 22.

ASSISTANT: Do you have any specifications?

USER: My departure time is evening.

ASSISTANT: I am sorry to say that there is no flight found under your details.

USER: No problem, thanks for checking.

ASSISTANT: Thank you for reaching us.