So how do you eliminate that fear? Imagine that you own a button that controls two lights: one red, the other green. Imagine that when you push this button, the green light is lit if the system works, and the red light is lit if the system is broken. Imagine that pushing that button and getting the result takes just a few seconds. How often would you push that button? You’d never stop. You’d push that button all the time. Whenever you made any change to the code, you’d push that button to make sure you hadn’t broken anything.
