.cs

public static partial class FunctionalExt
    {
        public static Tree<T> Reverse<T>(this Tree<T> @this) =>
        @this switch
        {
            Leaf<T> { Value: var v } => new Leaf<T>(v),
            Node<T> { Left: var l, Value: var v, Right: var r } =>
                                   new Node<T>(r.Reverse(), v, l.Reverse()),
        };

    }