Buying a car without keys

Back in the day, I had a '79 LeBaron, only New car I ever owned. While hastily loading the trunk to return from a fishing trip, I locked the keys in it. Luckily, I had a spare door/ignition key in my wallet and made the 8 hour trip home. Had a cooler of fish in that trunk so the first stop was our local town locksmith. He took an aluminum blank, inserted and turned it with a little pressure, then proceeded to file the knicks with a triangle file. repeated that a few more times and in a minute or two, he was in. Blew my mind. Charged me 10 bucks.