using System.Globalization;
TextInfo myTI = new CultureInfo("tr-tr",false).TextInfo;
Console.WriteLine($"\"{turkey}\".toUpper()");
Console.WriteLine($"Turkey: {myTI.ToUpper(turkey)}");
myTI = new CultureInfo("en-US",false).TextInfo;
Console.WriteLine($"English: {myTI.ToUpper(turkey)}");