Fences and outliers

You will write a function for the two fences, a function that lists the outliers, and a function that gives the ends of the whiskers in a box plot that marks outliers.

The idea. The fences are $Q_1 - k \times \text{IQR}$ and $Q_3 + k \times \text{IQR}$, with $k = 1.5$ unless you choose another value. An outlier is beyond a fence. Each whisker ends at the most extreme value inside the fences.

Your tasks.

1. Finish fences(data, k). Return the pair (low, high).
2. Finish outliers(data, k). Return a sorted list of the values beyond the fences.
3. Finish whiskers(data, k). Return the pair (smallest value inside the fences, largest value inside the fences).