sealed class Dumper
{
    static public string Dump(Node root) 
    {
        return Dump( root, "" );
    }
    static private string Dump(Node node, string indent)
    {
        return string.Format( "{0}\n{1}{2}", node.Text, 
            node.Children.Take(node.Children.Count - 1)
                .Aggregate("", (results, child) => string.Format( "{0}{1}├─{2}", results, indent, Dump(child, indent + "│ ") ) ),
            node.Children.Count == 0 ? "" : string.Format( "{0}└─{1}", indent, Dump(node.Children.Last(), indent + "  " ) ) );
    }
}