Loquacious XML builder

LoquaciousXml.cs

internal class NodeBuilder
{
    private readonly XmlDocument _doc;
    private readonly XmlNode _node;

    public NodeBuilder(XmlDocument doc, XmlNode node)
    {
        _doc = doc;
        _node = node;
    }

    public void SetAttribute(string name, string value)
    {
        var attribute = _doc.CreateAttribute(name);
        attribute.Value = value;
        _node.Attributes.Append(attribute);
    }

    public XmlNode AddNode(string name)
    {
        var newNode = _doc.CreateElement(name);
        _node.AppendChild(newNode);
        return newNode;
    }

    public void AddContent(string content)
    {
        _node.AppendChild(_doc.CreateTextNode(content));
    }
}

public interface INode
{
    void Attr(string name, string value);
    void Node(string name, Action<INode> action);
    void Content(string content);
}

internal class NodeImpl : INode
{
    private readonly XmlDocument _doc;
    private readonly NodeBuilder _nb;

    public NodeImpl(XmlDocument doc, XmlNode node)
    {
        _doc = doc;
        _nb = new NodeBuilder(doc, node);
    }

    public void Attr(string name, string value)
    {
        _nb.SetAttribute(name, value);
    }

    public void Node(string name, Action<INode> action)
    {
        action(new NodeImpl(_doc, _nb.AddNode(name)));
    }

    public void Content(string content)
    {
        _nb.AddContent(content);
    }
}

public static class Xml
{
    public static string Node(string name, Action<INode> action)
    {
        using (var stringWriter = new StringWriter())
        {
            var doc = new XmlDocument();
            var root = new NodeBuilder(doc, doc).AddNode(name);
            action(new NodeImpl(doc, root));

            doc.WriteTo(new XmlTextWriter(stringWriter));
            return stringWriter.ToString();
        }
    }
}