Switch4OrNothing.cs

using UdonSharp;
using UnityEngine;
using VRC.SDKBase;
using VRC.Udon;

public class Switch4OrNothing : UdonSharpBehaviour {
    public GameObject first;
    public GameObject second;
    public GameObject third;
    public GameObject fourth;

    public override void Interact() {
        if (this.first == null || this.second == null || this.third == null || this.fourth == null) {
            Debug.Log("Either the first, the second, the third, or the fourth has not set.");
            return;
        }
        var xs = new GameObject[] { first, second, third, fourth };

        for (var i = 0; i < xs.Length - 1; i++) {
            if (xs[i].activeSelf) {
                this.inactivateAll(xs);
                xs[i + 1].SetActive(true);
                return;
            }
        }

        xs[0].SetActive(true);
    }

    private void inactivateAll(GameObject[] xs) {
        foreach (var x in xs) {
            x.SetActive(false);
        }
    }
}