Extensions methods for traversing trees using recursion

RecursiveTreeExt.cs

    public static class RecursiveTreeExt
    {
        public static IEnumerable<T> AsDepthFirstEnumerable<T>(this T head, Func<T, IEnumerable<T>> children)
        {
            yield return head;
        
            foreach (var node in children(head))
            {
                foreach (var child in AsDepthFirstEnumerable(node, children))
                {
                    yield return child;
                }
            }
        }

        public static IEnumerable<T> AsBreadthFirstEnumerable<T>(this T head, Func<T, IEnumerable<T>> children)
        {
            yield return head;

            var last = head;
            foreach (var node in AsBreadthFirstEnumerable(head, children))
            {
                foreach (var child in children(node))
                {
                    yield return child;
                    last = child;
                }

                if (last.Equals(node)) 
                    yield break;
            }
        }
    }