Markup block - Gen<None> - 17 - (0:0,0)
    Markup span - Gen<Markup> - [test    ] - SpanEditHandler;Accepts:Any - (0:0,0) - Tokens:2
        HtmlTokenType.Text;[test];
        HtmlTokenType.WhiteSpace;[    ];
    Expression block - Gen<Expr> - 4 - (8:0,8)
        Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (8:0,8) - Tokens:1
            CSharpTokenType.Transition;[@];
        Code span - Gen<Expr> - [foo] - ImplicitExpressionEditHandler;Accepts:NonWhiteSpace;ImplicitExpression[RTD];K14 - (9:0,9) - Tokens:1
            CSharpTokenType.Identifier;[foo];
    Markup span - Gen<Markup> - [ test] - SpanEditHandler;Accepts:Any - (12:0,12) - Tokens:2
        HtmlTokenType.WhiteSpace;[ ];
        HtmlTokenType.Text;[test];
