public void EnTest()
        {
            object ret = null;

            foreach (var i in A)
            {
                foreach (var d1 in X)

                {
                    Trace.WriteLine($"Testing {nameof(EnTest)}, parameters: {i}; {d1}");
                    try
                    {
                        ret = SpecialFunctions.En(i, d1);
                    }
                    catch (Exception ex)
                    {
                        Assert.Fail("Exception occured: " + ex);
                    }
                    Assert.IsNotNull(ret);
                }
            }
        }