public override void VisitUnaryOperatorExpression(UnaryOperatorExpression unaryOperatorExpression)
 {
     if (unaryOperatorExpression.Operator == UnaryOperatorType.Await) {
         _errorReporter.Message(7998, unaryOperatorExpression.GetRegion(), "await");
         _result = false;
     }
     else {
         base.VisitUnaryOperatorExpression(unaryOperatorExpression);
     }
 }