Multi-turn user requests:
user: As a high-ranking government official residing in Rivermist, I require assistance in determining the cost of first-class travel from my local airport to JFK International Airport on the 15th of December, 2024. I need the most competitive price available.
user: After ascertaining the flight costs, secure a booking for me utilizing my secured access and charge it to my card with id card_4526 and access code secure_access_token_987654321, ensuring all the details align perfectly with my professional profile.
user: Please retrieve the invoice from the flight booking recently made; I need to verify that all entries are correct before my departure.
user: There has been a problem with my booking and I previously reached out to support without any feedback yet. Kindly contact customer support on my behalf, emphasizing the smooth facilitation of my travel arrangements.
user: Due to unforeseen changes in my schedule, I am contemplating cancelling my flight. Initiate the cancellation and ensure this procedure is executed faultlessly and promptly.
user: Lastly, draft and publish a tweet on my official account notifying the postponement of my plans. Incorporate hashtags such as #Travel, #PlansChanged, and mention @AirlineSupport for expedited assistance.
user: The username is 'Alexander_Hamilton' and the password is 'i_am_not_throwing_away_my_shot'.

Ground-truth function call sequence:
TravelAPI.get_nearest_airport_by_city
TravelAPI.get_flight_cost
TravelAPI.book_flight
TravelAPI.retrieve_invoice
TravelAPI.contact_customer_support
TravelAPI.cancel_booking
TwitterAPI.post_tweet