public static void Main()
var valueEmpty = string.Empty;
var valueNull = string.Empty;
Console.WriteLine(value.GetType() == typeof(string));
Console.WriteLine(value is string);
Console.WriteLine(valueEmpty.GetType() == typeof(string));
Console.WriteLine(valueEmpty is string);
Console.WriteLine(valueNull.GetType() == typeof(string));
Console.WriteLine(valueNull is string);