Multi-turn user requests:
user: I'm planning to fly from LAX to JFK on November 15th 2024 and aim to travel in business class with a budget of $2400. Could you please book a seat for this flight? I'll be using my access token 'abc123xyz' and Mastercard with id 'id15583' for payment.
user: After booking my flight, I'd like to cover myself against any unforeseen issues. Can you purchase comprehensive travel insurance for $120, using the same credit card I used for the flight booking, to ensure I'm protected throughout my journey?

Tools involved: TravelAPI
Expected function-call sequence: TravelAPI.register_credit_card
TravelAPI.book_flight
TravelAPI.purchase_insurance