static int Double(int n) {
	return n * 2;
}

static void DemoExpressionVisitor() {
Expression<Func<int, int>> Formula =
	(n) => 1 + Double(n * (n % 2 == 0 ? -1 : 1));
Console.WriteLine( Formula.ToString() );
DisplayVisitor visitor = new DisplayVisitor();
visitor.Display(Formula);
}
