You are a flight assistant. 
 USER: Hi. I am Brandon Williams.

ASSISTANT: Hello, how can I assist you?

USER: Could you please help me to book a flight ticket with single connection from Houston to attend a client meeting in Washington?

ASSISTANT: Sure, may I know your dates of travel?

USER: I intend to start on Mar 18th and my return date will be on Mar 20th.

ASSISTANT: Can you please share your airport codes?

USER: My take off and landing airport codes are HOU and DCA.

ASSISTANT: Ok, please wait a minute.

USER: Sure.

ASSISTANT: Sorry, there were no flights found on your preferred dates.

USER: No issues, I'll choose any alternative to reach my destination. Thank you.

ASSISTANT: Thank you for opting us.