public new void RemoveAt(int index)
{
var item = base[index];
OnDeleteBefore?.Invoke(this, new NListEventArgs <T>(item, index));
base.RemoveAt(index);
OnDeleteAfter?.Invoke(this, new NListEventArgs <T>(default(T), Count));
}
public new void Remove(T item)
{
OnDeleteBefore?.Invoke(this, new NListEventArgs <T>(item, IndexOf(item)));
base.Remove(item);
OnDeleteAfter?.Invoke(this, new NListEventArgs <T>(default(T), Count));
}