protected override FilterExpression Transform(FilterArrayExpression ax)
        {
            // This should probably go depth-first.

            if (ax.Elements.All(el => el is FilterConstantExpression))
            {
                return(new FilterConstantExpression(
                           new SequenceValue(ax.Elements
                                             .Cast <FilterConstantExpression>()
                                             .Select(ce => Representation.Recapture(ce.ConstantValue)))));
            }

            return(base.Transform(ax));
        }