(10 points) Prove that if both \(f(z)\) and \(\overline {f(z)}\) are holomorphic in a simply connected
domain then \(f\) is a constant function in that domain.
(10 points) Identify, with justification, the branch points of the function \[ f(z)=\frac {1}{\sqrt {(z+1)(z-i)}}. \]
Propose a corresponding branch cut.