Let $z=x+iy$ be a complex variable. Consider that contour integration is performed along the unit circle in anticlockwise direction. Which one of the following statements is NOT TRUE?
- The residue of $\frac{z}{z^2-1}$ at $z=1$ is $1/2$
- $\oint_C z^2 dz=0$
- $\frac{1}{2 \pi i} \oint_C \frac{1}{z} dz =1$
- $\overline{z}$ (complex conjugate of $z$ is an analytical function