public void MinimalFirstAnnualPercentageYield() =>
 Assert.Equal(0.5f, SavingsAccount.AnnualPercentageYield(0m));
 public void TinyFirstAnnualPercentageYield() =>
 Assert.Equal(0.5f, SavingsAccount.AnnualPercentageYield(0.000001m));
 public void MaximumFirstAnnualPercentageYield() =>
 Assert.Equal(0.5f, SavingsAccount.AnnualPercentageYield(999.9999m));