public void AgeInYears_PersonBorn1970_BeforeBirthdateIn2019_45()
        {
            var age = AgeInYears.Between(new DateTime(1970, 6, 26),
                                         new DateTime(2019, 5, 28));

            age.Should().Be(49.Years());
        }
        public void AgeInYears_PersonBorn1974_AfterBirthdateIn2019_45()
        {
            var age = AgeInYears.Between(new DateTime(1974, 6, 26), new DateTime(2019, 11, 28));

            Assert.Equal(45.Years(), age);
        }