public static class Test
{
	static bool Accept(string s) => s == "oob";

	public static bool Run()
	{
		string s = "foobar";
		Accept(s.Substring(1, 3)); //FAIL: cl
		bool b = Accept(s.Substring(1, 3));
		if (!b)
			return false;
		return Accept(s.Substring(1, 3));
	}
}