Is there a Linq method to add a single item to an IEnumerable?

Question

Basically I am trying to do something like this:

image.Layers

which returns an IEnumerable for all layers except the Parent layer,

Answer 1

I once made a nice little function for this:

public static class CoreUtil
{    
    public static IEnumerable AsEnumerable(params T[] items)
    {
        return items;
    }
}

Now this is possible:

image.Layers.Append(CoreUtil.AsEnumerable(image.ParentLayer, image.AnotherLayer))