/// <summary>
 /// Removes region ids from the RegionIds list.
 /// </summary>
 /// <param name="ids">The ids.</param>
 public void RemoveRegions(IEnumerable <int> ids)
 {
     foreach (int id in ids)
     {
         RegionIds.Remove(id);
     }
 }
 /// <summary>
 /// Removes a region id from the RegionIds list.
 /// </summary>
 /// <param name="id">The id.</param>
 public void RemoveRegion(int id)
 {
     RegionIds.Remove(id);
 }