RazorDocument - [0..7)::7 - [@is foo]
    MarkupBlock - [0..7)::7
        MarkupTextLiteral - [0..0)::0 - [] - Gen<Markup> - SpanEditHandler;Accepts:Any
            Marker;[];
        CSharpCodeBlock - [0..3)::3
            CSharpImplicitExpression - [0..3)::3
                CSharpTransition - [0..1)::1 - Gen<None> - SpanEditHandler;Accepts:None
                    Transition;[@];
                CSharpImplicitExpressionBody - [1..3)::2
                    CSharpCodeBlock - [1..3)::2
                        CSharpExpressionLiteral - [1..3)::2 - [is] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
                            Keyword;[is];
        MarkupTextLiteral - [3..7)::4 - [ foo] - Gen<Markup> - SpanEditHandler;Accepts:Any
            Whitespace;[ ];
            Text;[foo];
