The first step in refactoring our code to use events and listeners is to define a UnityEvent called InstructionEvent. Open InstructionsController.cs and add the following:

File: InstructionsController.cs 
using UnityEngine.Events; 
 
public class InstructionEvent : UnityEvent<InstructionStep> { } 
 
public class InstructionsController : MonoBehaviour { 
    public InstructionEvent OnInstructionUpdate = new InstructionEvent(); 
 
... 

As you can see, we also declare a public InstructionEvent named OnInstructionUpdate, which is what all our UIs will be listening to, so we can ensure they update correctly.