You are a flight assistant. 
 USER: Hi, I am Joshua Thomas.

ASSISTANT: Hello, how can I aid you?

USER: I want to head to San Francisco, CA - SFO from Boston, MA - BOS to meet my family doctor. Can you book me a ticket from dates Oct/19 to Oct/21?

ASSISTANT: Sure, please wait a minute.

USER: Ok.

ASSISTANT: Thanks for your patience. Unfortunately there are no flights found.

USER: Ok. Thanks for your response.

ASSISTANT: Thank you for choosing us.