class PersonImpl implements Person {
  protected String name;

  PersonImpl() {
    name ="Nobody";
  }

  PersonImpl(String name) {
    this.name = name;
  }

  public void say(String toSay) {
    System.out.println(name + " says: " + toSay);
  }

  public void introduceYourself() {
    say("Hi I'm " + name + ". How are you doing?");
  }
}