public static void AppendTag(this StringBuilder stringBuilder, string tagName, string content, object attributes)
 {
     stringBuilder.Append("<" + tagName);
     attributes.EachProperty(property => stringBuilder.Append(" " + property.Name.ToLower() + "=\"" + attributes.GetPropertyValue(property.Name) + "\""));
     stringBuilder.Append(">" + content);
     stringBuilder.AppendClosingTag(tagName);
 }
 public static void AppendUnorderedList(this StringBuilder stringBuilder, Action<StringBuilder> λ)
 {
     stringBuilder.AppendOpeningTag("ul");
     λ(stringBuilder);
     stringBuilder.AppendClosingTag("ul");
 }