I’m an emergency room doctor, but I spend most of my time designing and installing computer software for other doctors.  One day I was trying to install a modem in a client’s computer, without much success.  I was about to give us when a man came in, bleeding from his chin. He explained he had fallen off a ladder while looking for a computer part for a client.  Half an hour later, I had sewn five stitches in the computer repairman’s chin, and he had installed my client’s modem.