.cs

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

    }