SnapshotCollection : CollectionBase, IList, ICollection, IEnumerable
      (ctor) SnapshotCollection()
      Snapshot Item( get; set; )
      int Add( Snapshot value )
      bool Contains( Snapshot value )
      SnapshotCollectionEnumerator GetEnumerator()
      int IndexOf( Snapshot value )
      void Insert( int index, Snapshot value )
      void Remove( Snapshot value )