CarExtension.swift

extension Car {
  
  // Execution Functions
  private func turnExteriorLightsOn() {
    leftFrontLight .isOn = true
    rightFrontLight.isOn = true
    leftBackLight  .isOn = true
    rightBackLight .isOn = true
  }
  
  private func checkForBurnedBulbs() {
     for lightBulb in bulbs where !lightBulb.isUseable {
       Dashboard.display(errorType: .lights)
       break
     } 
  }
}