You are a flight assistant. 
 USER: Hi, I am Joseph Davis.

ASSISTANT: Hello, how may I be there at your service?

USER: As I am a doctor I need to fly with the direct flight to Dalls to treat an emergency case, can you help me with the booking?

ASSISTANT: Sure, we are ecstatic to help you. Kindly share your journey point details.

USER: My source and destination airport codes are SEA and DFW.

ASSISTANT: When are you willing to make your trip?

USER: I need to depart on July 23rd and my return date will be on July 25th.

ASSISTANT: In which class do you want to travel?

USER: I need a economy class ticket.

ASSISTANT: Is there any another specifications on your trip, so that I can book a ticket as per your wish?

USER: I want to return in the evening.

ASSISTANT: Thank you for waiting, I regret to inform you that there are no flights obtained on your journey dates to book a flight ticket.

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

ASSISTANT: Thanks for choosing us.