写一个订阅发布模式

• 按照输出结果补全代码

class EventEmeitter{
    constructor(){
        this._events = this._events || new Map();
    }
}

EventEmeitter.protype.emit = function (type, ...args) {
    write your code
    // this._events.get(type)(...args);
}

EventEmeitter.protype.addListener = function (type, fn) {
    write your code
    // this.events.set(type, fn);
}

EventEmeitter.protype.removeListener = function (type, fn) {
    write your code
    // this.events.delete(type);
}

const emitter = new EventEmeitter();
emitter.addListener('jswp', name => {
    console.log(`wp: ${name}`);
});
emitter.addListener('jswp', name => {
    console.log(`wp1: ${name}`);
});
emitter.emit('jswp', 'jswp');
打印结果要求： wp: jswp  wp1: jswp