Let's look at the steps for implementation: 

1. We'll start by writing a core element of the pattern, the Visitor interface:

namespace Pattern.Visitor
{
    public interface IVisitor
    { 
        void Visit(BikeShield bikeShield);
        void Visit(BikeEngine bikeEngine);
        void Visit(BikeWeapon bikeWeapon);
    }
}

2. Next up, we are going to code an interface that each visitable element will have to implement:

namespace Pattern.Visitor
{
    public interface IBikeElement
    { 
        void Accept(IVisitor visitor);
    }
}

3. Now that we have our primary interfaces, let's implement the main class that makes our power-up mechanism work; because of its length, we will review it in two parts:

using UnityEngine;

namespace Pattern.Visitor
{
    [CreateAssetMenu(fileName = "PowerUp", menuName = "PowerUp")]
    public class PowerUp : ScriptableObject, IVisitor
    {
        public string powerupName;
        public GameObject powerupPrefab...