using System;

public class Program

{

    public static void Main()

    {

        string tab = "\t";

        string returnNewLine = "\r\n";

        string notWhiteSpace = "/\t";

        string lotsOfSpaces = "          ";

        if (String.IsNullOrWhiteSpace(tab)) Console.WriteLine("tab is whitespace");

        if (string.IsNullOrWhiteSpace(returnNewLine)) Console.WriteLine("return new line is whitespace");

        if (string.IsNullOrWhiteSpace(lotsOfSpaces)) Console.WriteLine("lots of spaces is whitespace");

        if (string.IsNullOrWhiteSpace(notWhiteSpace)) Console.WriteLine("there's a problem");

    }

}