iterator property 
    
    
        
  
    
    
  
Gets the item at the specified index.
The zero-based index of the item to get.
Gets an enumerator that iterates through the elements of the collection.
    
  Implementation
  // TItem this[int index]
//        {
//            get
//            {
//                if (index < 0 || index >= this.Count)
//                {
//                    throw new ArgumentOutOfRangeException("index", Strings.IndexIsOutOfRange);
//                }
//
//                return this.items[index];
//            }
//        }
/// <summary>
/// Gets an enumerator that iterates through the elements of the collection.
/// </summary>
/// <returns>An IEnumerator for the collection.</returns>
@override
Iterator<TItem> get iterator => this.items.iterator;