CSharpCodeBlock - [0..15)::15 - [@val?[abc]?[def]
    CSharpImplicitExpression - [0..15)::15
        CSharpTransition - [0..1)::1 - Gen<None> - SpanEditHandler;Accepts:None
            Transition;[@];
        CSharpImplicitExpressionBody - [1..15)::14
            CSharpCodeBlock - [1..15)::14
                CSharpExpressionLiteral - [1..15)::14 - [val?[abc]?[def] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:Any;ImplicitExpression[RTD];K14
                    Identifier;[val];
                    QuestionMark;[?];
                    LeftBracket;[[];
                    Identifier;[abc];
                    RightBracket;[]];
                    QuestionMark;[?];
                    LeftBracket;[[];
                    Identifier;[def];
