Miscellaneous helper functions to work with Enumerations

IterTools.cs

public static class IterTools
{
    private static readonly Random Random = new Random();

    /// <summary>
    /// Make an enumeration with a single element.
    /// </summary>
    /// <typeparam name="T">The type of the enumeration elements.</typeparam>
    /// <param name="element">The single element to enumerate.</param>
    /// <returns>A reference to the enumeration.</returns>
    public static IEnumerable<T> ToAtom<T>(this T element)
    {
        yield return element;
    }

    /// <summary>
    /// Splits an enumeration into fixed length partitions.
    /// </summary>
    /// <typeparam name="T">The enumeration type.</typeparam>
    /// <param name="source">The source enumeration.</param>
    /// <param name="size">The maximum size of each partition.</param>
    /// <returns>A reference to the enumeration.</returns>
    /// <exception cref="NullReferenceException">If <paramref name="source"/> is null.</exception>
    public static IEnumerable<T[]> Parititon<T>(this IEnumerable<T> source, int size)
    {
        return PartitionHelper(source, size);
    }

    /// <summary>
    /// Splits a sequence of chars into fixed length strings.
    /// </summary>
    /// <param name="source">The source enumeration.</param>
    /// <param name="size">The maximum size of each partition.</param>
    /// <returns>A reference to the enumeration.</returns>
    /// <exception cref="NullReferenceException">If <paramref name="source"/> is null.</exception>
    public static IEnumerable<string> Parititon(this IEnumerable<char> source, int size)
    {
        return PartitionHelper(source, size).Select(x => new string(x));
    }

    /// <summary>
    /// Picks random elements out of an enumeration.
    /// </summary>
    /// <typeparam name="T">The enumeration type.</typeparam>
    /// <param name="source">The source enumeration.</param>
    /// <param name="count">The maximum number of items to return.</param>
    /// <returns>A reference to the enumeration.</returns>
    /// <exception cref="NullReferenceException">If <paramref name="source"/> is null.</exception>
    public static IEnumerable<T> Sample<T>(this IEnumerable<T> source, int count)
    {
        return source.Select(item => new { Key = Random.NextDouble(), Value = item })
                    .OrderBy(pair => pair.Key)
                    .Take(count)
                    .Select(pair => pair.Value);
    }

    private static IEnumerable<T[]> PartitionHelper<T>(IEnumerable<T> items, int size)
    {
        return items.Select((value, index) => new { value, index })
                    .GroupBy(x => x.index / size)
                    .Select(x => x.Select(v => v.value).ToArray());
    }
}