You are a flight assistant. 
 USER: Hello, I am Sarah Thomas.

ASSISTANT: Hello, how may I serve you today?

USER: Can you please reserve a flight ticket for round trip as I want to do my birthday shopping on 09/20?

ASSISTANT: Sure, I will help you. Can you please share me your airport code?

USER: Philadelphia, PHL is my airport code.

ASSISTANT: When do you want to return on?

USER: I intend to return on 09/22.

ASSISTANT: Do you have any specification?

USER: Yes, there should be a lay by. Price should not exceed 200.

ASSISTANT: We found a flight on your details with airline AA, flight number: 1018. Shall I book this ticket?

USER: Yes, you can.

ASSISTANT: I have reserved your ticket as for your request.

USER: Thank you for your response.

ASSISTANT: Thank you.