/// <summary>
/// Remove observer
/// </summary>
/// <param name="observer"></param>
public void Detach(INewsSourceObserver observer)
{
_observers.Remove(observer);
}
/// <summary>
/// Add observer
/// </summary>
/// <param name="observer"></param>
public void Attach(INewsSourceObserver observer)
{
_observers.Add(observer);
}
