Let \(f(z)\) be analytic inside and on a simple closed contour \(C\) except for a
finite number of poles inside \(C .\) Denote the zeros by \(z_{1}, \ldots, z_{n}\)
(none of which lies on \(C\) ) and the poles by \(w_{1}, \ldots, w_{m} .\) If
\(g(z)\) is analytic inside and on \(C\), prove that
$$
\frac{1}{2 \pi i} \int_{C} g(z) \frac{f^{\prime}(z)}{f(z)} d z=\sum_{j=1}^{n}
g\left(z_{j}\right)-\sum_{j=1}^{m} g\left(w_{j}\right)
$$
where each zero and pole occurs as often in the sum as is required by its
multiplicity.