An example of extension methods in C#

ThreadExtension.cs

using System;
using System.Collections.Concurrent;
using System.Threading;

namespace ReadWriteBuffer
{
    public static class ThreadExtension
    {
        private const LocalDataStoreSlot PRIORITY_SLOT = Thread.GetNamedDataSlot("prioritySlot");
        public static ThreadPriority GetPriority(this Thread t)
        {
            object data = Thread.GetData(PRIORITY_SLOT);
            return (data == null) ?
                ThreadPriority.Normal : (ThreadPriority)data;
        }
        public static void SetPriority(this Thread t, ThreadPriority p)
        {
            Thread.SetData(PRIORITY_SLOT, p);
        }
    }
}