public void Detect_Multiple_Of(int prime, int number) =>
 FooBarQix.Test(number)
 .Should()
 .ContainSingle(x => IsMultipleOfMatch(x, prime));
 public void Detect_Digit_At(int digit, int index, int number) =>
 FooBarQix.Test(number)
 .Should()
 .ContainSingle(x => IsDigitAtMatch(x, digit, index));
 public void Detect_None(int number) =>
 FooBarQix.Test(number)
 .Should()
 .BeEmpty();