internal void AddSequenceQueryOption(QueryOptionExpression qoe)
        {
            Debug.Assert(qoe != null, "qoe != null");
            QueryOptionExpression old = this.sequenceQueryOptions.Where(o => o.GetType() == qoe.GetType()).FirstOrDefault();
            if (old != null)
            {
                qoe = qoe.ComposeMultipleSpecification(old);
                this.sequenceQueryOptions.Remove(old);
            }

            this.sequenceQueryOptions.Add(qoe);
        }