Markup block - Gen<None> - 12 - (0:0,0)
    Markup span - Gen<Markup> - [] - SpanEditHandler;Accepts:Any - (0:0,0) - Tokens:1
        SyntaxKind.Unknown;[];
    Expression block - Gen<Expr> - 8 - (0:0,0)
        Transition span - Gen<None> - [@] - SpanEditHandler;Accepts:None - (0:0,0) - Tokens:1
            SyntaxKind.Transition;[@];
        Code span - Gen<Expr> - [Section] - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K15 - (1:0,1) - Tokens:1
            SyntaxKind.Identifier;[Section];
    Markup span - Gen<Markup> - [ foo] - SpanEditHandler;Accepts:Any - (8:0,8) - Tokens:2
        SyntaxKind.Whitespace;[ ];
        SyntaxKind.Text;[foo];
