get_flight_cost(travel_from='LAX', travel_to='JFK', travel_date='2024-04-15', travel_class='business')
book_flight(access_token='abc123xyz', card_id='card_123456789', travel_date='2024-04-15', travel_from='LAX', travel_to='JFK', travel_class='business')
retrieve_invoice(access_token='abc123xyz', booking_id='3426812')
contact_customer_support(booking_id='3426812', message='There were hiccups during the booking process. Please assist.')
message_login(user_id='USR001')
send_message(receiver_id='USR003', message='Update on flight issue and customer support contact.')
view_messages_sent()