You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Alexander Hernandez.

ASSISTANT: How can I assist you?

USER: I am planning to celebrate my sister's birthday at SFO. Can you please help me to book a flight from DFW?

ASSISTANT: Sure, I am here to help you.

USER: Thank you.

ASSISTANT: Could you please provide your journey dates as per your schedule?

USER: Sure, my preferable journey dates are Dec 10 - Dec 12.

ASSISTANT: May I know your connection limit?

USER: I need a flight with single connection.

ASSISTANT: Which class would you prefer for your journey?

USER: I am comfortable with any class to travel.

ASSISTANT: Do you have any other preferences?

USER: Yes, my depart time should be on evening.

ASSISTANT: Give me a minute, I will check and revert to you.

USER: Sure, take your time.

ASSISTANT: Thank you for your time. I am sorry to inform you that, there are no flights leaving from DFW in the evening time.

USER: Ok, not an issue. Thank you for the information.

ASSISTANT: Thank you for approaching us.