list_all_airports()
get_flight_cost(travel_from='RMS', travel_to='SBK', travel_date='2024-12-15', travel_class='business')
set_budget_limit(access_token='12345-67890', budget_limit=2000.0)
purchase_insurance(access_token='12345-67890', insurance_type='comprehensive', booking_id='d184e2c0-2ebb-4f39-a525-d5e01b67dc6c', insurance_cost=300.0, card_id='0001')
retrieve_invoice(access_token='12345-67890', booking_id='d184e2c0-2ebb-4f39-a525-d5e01b67dc6c')