Example Extension Methods

EnumerableExtensions.cs

public static class EnumerableExtensions
{
    public static void ForEach<T>(this IEnumerable<T> items, Action<T> action)
    {
        foreach (var item in items)
            action(item);
    }
}

HashCodeHelper.cs

public static class HashCode
{
    public static int ComputeHashCode(params object[] logicalKeys)
    {
        var hash = 13;
        foreach (var logicalKey in logicalKeys)
        {
            hash = hash * 7 + (logicalKey == null ? 0 : logicalKey.GetHashCode());
        }
        return hash;
    }
}

IntegerExtensions.cs

public static class IntegerExtensions
{
    public static void Times(this int n, Action<int> action)
    {
        Enumerable.Range(0, n).ForEach(action);
    }
}

public void Foo() {
  10.Times(x => DoSomethingWith(x));
}