text: class Boss extends Enemy {
    constructor() {
      super(ENEMY_BOSS_LANE, 'boss', enemy_boss_image, null,
            ENEMY_BOSS_WIDTH, ENEMY_BOSS_HEIGHT);
  
      this.lives = boss_lives;
      this.rotate = 0;
      this.rotation = 0.5;
      this.bullet_rotate = 0;
      this.bullet_rotation = -0.1;
    }
  
    updateBullets() {
      this.bullets.forEach(bullet => {
        bullet.update(1, this.bullet_rotate);
  
        this.bullet_rotate += this.bullet_rotation;
  
        if (this.bullet_rotate >= 8) this.bullet_rotation = -0.1;
        if (this.bullet_rotate <= -8) this.bullet_rotation = 0.1;
      });
    }
  
    shoot() {
      this.bullets.push(new Bullet(this, ENEMY_BULLET_OFFSET,
                                   ENEMY_BOSS_BULLET_OFFSET_Y,
                                   enemy_bullet_image));
  
      this.bullets.push(new Bullet(this, ENEMY_BOSS_BULLET_OFFSET_X,
                                   ENEMY_BOSS_BULLET_OFFSET_Y,
                                   enemy_bullet_image));
    }
  
    update() {
      if (this.y < BOSS_Y_POS) {
        this.y = this.y + 2;
        this.domElement.style.top = `${this.y}px`;
      }
      else {
        if (this.rotate > 30) this.rotation = -0.5;
        if (this.rotate < -30) this.rotation = 0.5;
  
        this.rotate += this.rotation;
        this.domElement.style.transform = `rotate(${this.rotate}deg)`;
      }
    }
  }
  