/// <summary>
		/// combines two search hits that refer
		/// to the same record. all the extended
		/// properties such as ranking and index specific
		/// information should be combined.
		/// </summary>
		/// <param name="other">the SearchHit that 
		/// should be combined to this one</param>
		public void Combine(SearchHit other)
		{
		}
		/// <summary>
		/// Adds a new item to the collection of items
		/// returned by the search. If the hit
		/// represents an existing record it
		/// will be combined to the existing hit instead.
		/// </summary>
		/// <param name="hit">the hit to be added or
		/// combined to a existing hit</param>
		public void Add(SearchHit hit)
		{
			SearchHit existing = FindSearchHit(hit.Record);
			if (null != existing)
			{
				existing.Combine(hit);
			}
			else
			{
				_hits.Add(hit);
			}
		}