protected virtual void VisitIsInstanceOfTypeExpression(IsInstanceOfTypeExpression isInstanceOfTypeExpression)
 {
     VisitExpression(isInstanceOfTypeExpression);
     VisitTypeReferenceIfNotNull(isInstanceOfTypeExpression.Type);
     Visit(isInstanceOfTypeExpression.Expression);
 }
 protected virtual void WriteIsInstanceOfTypeExpression(IndentedTextWriter writer, IsInstanceOfTypeExpression expression)
 {
     writer.Write("(");
     WriteExpression(writer, expression.Expression);
     writer.Write(" is ");
     WriteTypeReference(writer, expression.Type);
     writer.Write(")");
 }