Plaintiff Wall drove his car into a self-parking lot at O’Hare Airport in Chicago. He entered through an automatic gate and received a ticket bearing the date and time of arrival. He parked, locked the car, and left with the keys. Normally, when ready to depart, he would walk to his car and, using his keys, would enter the car and drive it to the exit. There an attendant would take the ticket and compute and collect the parking fee. This time his car had been stolen. He sued the defendant, Airport Parking Company of Chicago, for damages. Is the defendant liable? (Wall v. Airport Parking Company of Chicago, 244 N.E.2d 190, 41 Ill. 2d 506)