"""Chapter 5, example 1
Some simple statistical functions.
>>> from ch_5_ex_1 import mean, median
>>> data = [2, 4, 4, 4, 5, 5, 7, 9]
>>> data # doctest: +ELLIPSIS
[2, 4..., 9]
>>> mean( data )
5.0
>>> median( data )
4.5
"""
