protected override Expression VisitInvocation(InvocationExpression node)
        {
            Out("Invoke(");
            Visit(node.Expression);
            string sep = ", ";

            for (int i = 0, n = node.ArgumentCount(); i < n; i++)
            {
                Out(sep);
                Visit(node.GetArgument(i));
            }
            Out(')');
            return(node);
        }