You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: Susan Rodriguez here.

ASSISTANT: How can I assist you today?

USER: Actually, I am looking for a direct flight in my journey, can you please help me out with booking of a flight ticket?

ASSISTANT: Sure, will you mention your travelling dates please?

USER: I am planning to leave my location on 12/23 and please book my return ticket on 12/25.

ASSISTANT: Please provide your travelling dates. Please provide your airport codes.

USER: I will prefer IAH and DCA as my origin and destination airport codes.

ASSISTANT: Please give me a moment.

USER: Sure, take your time.

ASSISTANT: Thanks for waiting, there is no flights available under your details.

USER: Oh! So sad to hear that. Anyway, thank you for the information.

ASSISTANT: Welcome, have a great day.