public static IEnumerable <Item> GetEnumeratedItems(this Region region)
{
List <Item> list = region.GetItems();
IEnumerable <Item> e;
lock (_ItemLock)
{
e = list.AsParallel().Where(i => i != null && i.GetRegion().IsPartOf(region));
}
foreach (Item item in e)
{
yield return(item);
}
list.Clear();
list.TrimExcess();
}