public T visit<T>(object arg, params object[] extrasArgs)        {            var methed=from m in GetType().GetMethods()                       where m.Name == "Visit" && m.GetParameters().Length == 1 + extraArgs.Length                               && arg.GetType().IsAssignableFrom(m.GetParameters()[0].ParameterType)                               && m.ReturnType == typeof(T)                       orderby m.GetParameters()[0].ParameterType.Name == arg.GetType().Name descending, m.GetParameters()[0].ParameterType.Name ascending                       select m;            return (T)method.First().Invoke(this, new[] { arg }.Concat(extraArgs).ToArray());        }  今天看OXITE的Visitor，結果看的一頭霧水，，麻煩哪位大俠給解釋一下，，，（1）public T visit<T>(object arg, params object[] extrasArgs)這種寫法是什么意思（2）麻煩對這個方法里面的代碼解釋一下小弟拜謝