You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you?

USER: Justin Turner here, I was planning to visit my kids for this summer, can you book a flight from 04/11 to 04/13.

ASSISTANT: Sure, can I know your airport codes.

USER: My desired airport codes for the following journey will be from DEN - HOU.

ASSISTANT: Give me a minute. Turner, there is no flight available on your requested dates.

USER: Oh! That's sad to hear, thank you for assisting me with your services.

ASSISTANT: You are welcome.

USER: Thank you for checking with availability.