The branch cut in this example doesn't have to lie along the real axis.
That is, we make the definition that agrees along the real axis.
Hue varies with argument, or angle, measured from the positive real axis.
Real power does do work, so it is the real axis.
There may, however, be limit points on the real axis.
I knew marketing was the real axis of evil.
Such a function is real at the real axis.
Thus they lie all on the real axis.
This expansion is valid for in any sector not containing the negative real axis with large.
In fact, these numbers may be constrained to be on the real axis.