A five-number summary function

You will write your own median, then a function that returns the five-number summary with the rule of this chapter, and a function for the IQR.

The idea. Sort the data. The median is the middle value, or the mean of the two middle values. With an odd count, leave the median out of both halves. The quartiles are the medians of the halves.

Your tasks.

1. Finish median_of(values).
2. Finish five_numbers(data). Return a list [minimum, q1, median, q3, maximum].
3. Finish iqr(data).