CSharpCodeBlock - [0..20)::20 - [@val?[abc?.gef?[-1]]]
    CSharpImplicitExpression - [0..20)::20
        CSharpTransition - [0..1)::1 - Gen<None> - SpanEditHandler;Accepts:None
            Transition;[@];
        CSharpImplicitExpressionBody - [1..20)::19
            CSharpCodeBlock - [1..20)::19
                CSharpExpressionLiteral - [1..20)::19 - [val?[abc?.gef?[-1]]] - Gen<Expr> - ImplicitExpressionEditHandler;Accepts:NonWhitespace;ImplicitExpression[RTD];K14
                    Identifier;[val];
                    QuestionMark;[?];
                    LeftBracket;[[];
                    Identifier;[abc];
                    QuestionMark;[?];
                    Dot;[.];
                    Identifier;[gef];
                    QuestionMark;[?];
                    LeftBracket;[[];
                    Minus;[-];
                    IntegerLiteral;[1];
                    RightBracket;[]];
                    RightBracket;[]];
