public void ExecuteInMemory()
        {
            var items  = new[] { 1, 2, 3 };
            var input  = new StreamedSequence(items, new StreamedSequenceInfo(typeof(int[]), Expression.Constant(0)));
            var result = _resultOperator.ExecuteInMemory <int> (input);

            Assert.That(result.GetTypedSequence <int>().ToArray(), Is.EquivalentTo(new[] { 1, 2, 3 }));
        }