You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you?

USER: I am planning to visit Washington, can you please book me a ticket from HOU to IAD?

ASSISTANT: May I know your desired travel dates please?

USER: My preferable journey dates are from 10/22 to 10/24.

ASSISTANT: May I know your name please?

USER: My name is Sandra Nelson.

ASSISTANT: There is no flight available on your desired travel dates.

USER: Ok, not an issue. I will find any alternate for this trip. Thank you.

ASSISTANT: Thank you for opting us.