how to use customized c# attributes

gistfile1.cs

using System;
using System.Collections.Generic;
using Microsoft.VisualStudio.TestTools.UnitTesting;

namespace RTP_Composite
{
  
    [TestClass]
    public class AttributeSpike
    {
        [TestMethod]
       public void TryAttributes()
       {
           Sut sut = new Sut();

           var keys = new List<string> {"toc", "print"};

           foreach ( var method in typeof (Sut).GetMethods())
           {
               var attr = (LoadFromXmlAttribute)Attribute.GetCustomAttribute(method, typeof(LoadFromXmlAttribute)); 

               if ( attr!=null &&  keys.Contains(attr.Key))
               {
                   method.Invoke(sut, null);
               }
           }
       }
    }

    class Sut
    {
        [LoadFromXml("toc")]
        public void MethodA()
        {
            Console.WriteLine("Method A called");
        }

        [LoadFromXml("print")]
        public void MethodB()
        {
            Console.WriteLine("Method B called");
        }

        [LoadFromXml("oops")]
        public void MethodC()
        {
            Console.WriteLine("Method C called");
        }
    }

    [AttributeUsage(AttributeTargets.Method)]
    internal sealed class LoadFromXmlAttribute : Attribute
    {
        private readonly string m_key;

        public LoadFromXmlAttribute(string key)
        {
            m_key = key;
        }

        public string Key
        {
            get { return m_key; }
        }
    }
}