public void StaticTests()
 {
     Assert.AreEqual(Kalkulator.BasicOp('+', 4, 7), 11);
     Assert.AreEqual(Kalkulator.BasicOp('-', 15, 18), -3);
     Assert.AreEqual(Kalkulator.BasicOp('*', 5, 5), 25);
     Assert.AreEqual(Kalkulator.BasicOp('/', 49, 7), 7);
 }