static void MainInterfaces()
    {
        var john = new Client {
        Name = "John Doe", Income = 40000, YearsInJob = 1,
        UsesCreditCard = true, CriminalRecord = false
          };

        // Create instance & call method of the class
        var test = new CoefficientTest(0.001, 5.0, 50.0);
        test.PrintInfo();

        // Cast to the interface type & call interface method
        var cltest = (IClientTest)test;
        if (cltest.Test(john)) cltest.Report(john);
    }
    static void MainInterfaces()
    {
        var john = new Client {
            Name           = "John Doe", Income = 40000, YearsInJob = 1,
            UsesCreditCard = true, CriminalRecord = false
        };

        // Create instance & call method of the class
        var test = new CoefficientTest(0.001, 5.0, 50.0);

        test.PrintInfo();

        // Cast to the interface type & call interface method
        var cltest = (IClientTest)test;

        if (cltest.Test(john))
        {
            cltest.Report(john);
        }
    }