Although ordinary functions can be evaluated at compile time without the constexpr annotation, only constexpr functions will raise an error if it _can't_ be eva

Although ordinary functions can be evaluated at compile time without the constexpr annotation, only constexpr functions will raise an error if it _can't_ be evaluated at compile time (irrespective of if the compile thinks it should be). it's a judgement call for when explicit intent > implicit side-effects.