T3、编写程序实现乐手弹奏乐器。乐手可以弹奏不同的乐器从而发出不同的声音。可以弹奏的乐器包括二胡、钢琴和琵琶。要求：

1. 定义乐器类Instrument，包括方法makeSound()
2. 定义乐器类的子类：二胡Erhu、钢琴Piano和小提琴Violin
3. 定义乐手类Musician，可以弹奏各种乐器play(Instrument instrument)
4. 定义测试类，给乐手不同的乐器让他弹奏。

public class Instrument {//父类
    public void makeSound(){
        System.out.println("乐器发出声音");
    }
}

public class Erhu extends Instrument{//子类1
    public void makeSound() {
        System.out.println("乐手弹奏二胡，发出二胡声");
    }
}

public class Piano extends Instrument{//子类2
    public void makeSound() {
        System.out.println("乐手弹奏钢琴，发出钢琴声");
    }
}

public class Violin extends Instrument{//子类3
    public void makeSound() {
        System.out.println("乐手弹奏小提琴，发出小提琴声");
    }
}

public class Musician {//乐手类
    //类Musician 有方法play(Instrument instrument)
    public void play(Instrument instrument){
        instrument.makeSound();
    }
}

public class TestMusic {//测试类
    public static void main(String[] args) {
        Musician musician = new Musician();
        Erhu erhu = new Erhu();
        Piano piano = new Piano();
        Violin violin = new Violin();

        musician.play(erhu);
        musician.play(piano);
        musician.play(violin);
    }
}