It’s Saturday night, and the software developer needs to make a grocery run. Before he leaves, his wife tells him, “Buy a gallon of milk, and if there are eggs, buy a dozen.” So he makes the trip, purchases the dairy, and returns home. When he walks in, though, his wife is confused. “Why did you get 13 gallons of milk?” she exclaims. “…Because there were eggs!” the developer replies.
