public void NumericsOnlyWorks()
{
Assert.AreEqual(string.Empty, MHString.NumericsOnly("abcdef"), "t1");
Assert.AreEqual("123", MHString.NumericsOnly("abc123"), "t2");
Assert.AreEqual("123", MHString.NumericsOnly("abcdefghijklmnopqrstuv123"), "t3");
Assert.AreEqual(string.Empty, MHString.NumericsOnly("adkhfkekhqhbeebfeb*@#&#^#^ dki"), "t4");
}