Enlarge (credit: Getty / Aurich Lawson / Tesla) There's an old joke in the software engineering world, sometimes attributed to Tom Cargill of Bell Labs: "the first 90 percent of the code accounts for the first 90 percent of the development time. The remaining 10 percent of the code accounts for the other 90 percent of the development time." On Monday, Tesla held a major event to show off the company's impressive progress toward full self-driving technology.