class Subject {
  constructor() {
    this.observers = [];
  }
  add(observer) {
    this.observers.push(observer);
  }
  remove(observer) {
    this.observers = this.observers.filter((iO) => iO !== observer);
  }
  notify(...args) {
    this.observers.forEach((f) => f(...args));
  }
}

module.exports.Subject = Subject;