Check out example codes for "unityevent". It will help you in understanding the concepts better.
Code Example 1
using UnityEngine.Events;
// UnityEvents can also be serialized to the inspector
public class Foo : MonoBehaviour {
UnityEvent action;
void Start() {
action = new UnityEvent();
action.AddListener(() => { Debug.Log("Hello world!"); });
}
void Update() {
action.Invoke();
}
}
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