Prove that the value of \(\int_{u_0}^{u_0+2\omega} \wp(u)du\) is independent of \(u_0\), the integral being taken along any path not passing through a pole of \(\wp(u)\). If \(l = \int_{u_0}^{u_0+2\omega}\wp(u)du\), \(l' = \int_{u_0}^{u_0+2\omega'}\wp(u)du\), prove that \[ \omega l' - \omega'l = \pi i. \]