Extend the Stats module with the function max_list/1 which returns the maximum number in a list.

max_list([]) should return the atom :undefined.

Hints: * What is the maximum of [e]? (A one element list.) * What is the maximum of [h|t]? * Use the built-in max/2 function to get the maximum of two numbers.

Here is some sample output of how it should work:

iex(1)> xs = [10, 15, 13 , 5, 3, 2, 20, 25, 23]
[10, 15, 13, 5, 3, 2, 20, 25, 23]
iex(2)> Stats.max_list(xs)
25
iex(3)> Stats.max_list([1,2,3])
3
iex(4)> Stats.max_list([5,4,3])
5
iex(5)> ys = for x <- -10..10, do: x*x - 3*x
[130, 108, 88, 70, 54, 40, 28, 18, 10, 4, 0, -2, -2, 0, 4, 10, 18, 28, 40, 54,
 70]
iex(6)> Stats.max_list(ys)
130

Try sampling your Die.roll/0 function a couple of times and see what the maximum is.