private void OnCollisionEnter2D(Collision2D collision)
    {
        /*
         * // if the bullet is a player bullet and it hits the enemy, subtract health
         * if (gameObject.tag == "PlayerBullet")
         *  if (collision.gameObject.tag == "Enemy")
         *      collision.gameObject.GetComponent<EnemyManager>().Health-= PlayerFire.instance.gun.WeaponDamage;
         */

        // create an explosion and destroy the bullet
        StartCoroutine(Effects.BulletHitEffect(gameObject));
    }