// Introduced in Chapter 3/** A flashing, colored light bulb. */public class FlashingColoredLight extends ColoredLight {  /** No special initialization is required. */  public FlashingColoredLight() {    super();  }  /** Toggle the light's on status after returning a String. */  public String toString() {    String result;    if (isOn()) {      result = "" + getColor();    } else {      result = ".";    }    setOn(!isOn());    return result;  }}