Markup block - Gen<None> - 18 - (0:0,0)
    Tag block - Gen<TagHelper> - 18 - (0:0,0) - p - pTagHelper
        StartTagAndEndTag - <p class="btn"  ... </p
        class - DoubleQuotes
            Markup span - Gen<Markup> - [btn] - SpanEditHandler;Accepts:Any - (10:0,10) - Tokens:1
                HtmlTokenType.Text;[btn];
