void FromRedToGreen()
 {
   color = Color.Green;
   toNextLight = new Timer(FromGreenToYellow, 6.0f);
 }
 void FromGreenToYellow()
 {
   color = Color.Yellow;
   toNextLight = new Timer(FromYellowToRed, 6.0f);
 }
 void FromYellowToRed()
 {
   color = Color.Red;
   toNextLight = new Timer(FromRedToGreen, 6.0f);
 }
 public TrafficLight()
 {
   color = Color.Green;
   toNextLight = new Timer(FromGreenToYellow, 6.0f);
 }