Helpful C# IEnumerable extension methods

Append.cs

public static class AppendExtensions
{
    public static IEnumerable<V> Append<V>(this V val, IEnumerable<V> enumerable)
    {
        yield return val;
        foreach (V v in enumerable) yield return v;
    }

    public static IEnumerable<V> Append<V>(this IEnumerable<V> enumerable, V val)
    {
        foreach (V v in enumerable) yield return v;
        yield return val;
    }
}