1.0.shouldApprox == 1 + 9e-7;
shouldApprox(1 + 9e-7, 1e-6, 1e-6) == 1;

static struct C {
    double re, im;
    auto approxEqual(C rhs, double maxRelDiff, double maxAbsDiff)
    {
        import mir.math.common: approxEqual;
        return approxEqual(re, rhs.re, maxRelDiff, maxAbsDiff) && approxEqual(im, rhs.im, maxRelDiff, maxAbsDiff);
    }
}
C(1.0, 1.0).shouldApprox == C(1 + 9e-7, 1 - 9e-7);