using System.Collections.Generic;

// Using an abstract class to avoid repeating code, but could be implemented as an interface if inheritance is somehow needed for the subjects
public abstract class Observable
{
    private List<IObserver> observers;

    public Observable()
    {
        observers = new List<IObserver>();
    }

    public void Subscribe(IObserver observer)
    {
        observers.Add(observer);
    }

    public void UnSubscribe(IObserver observer)
    {
        observers.Remove(observer);
    }

    public void NotifyObservers()
    {
        foreach (IObserver observer in observers)
        {
            observer.Notify();
        }
    }
}