public void None()
{
Result <int, Exception> res1 = new Ok <int, Exception>(1);
Assert.Equal(typeof(None <Exception>), res1.None().GetType());
Assert.Throws <InvalidOperationException>(() => res1.None().Unwrap());
Result <int, string> res2 = new Err <int, string>("error message.");
Assert.Equal(typeof(Some <string>), res2.None().GetType());
Assert.Equal("error message.", res2.None().Unwrap());
}
