Exercise $1$

Please complete the sigmoid function to calculate

$g(z)=\frac{1}{1+e^{-z}}$

Note that

$,$ is not always a single number, but can also be an array of numbers.

If the input is an array of numbers, we'd like to apply the sigmoid function to each value in the input array.

If you get stuck, you can check out the hints presented after the cell below to help you with the implementation.