Problem: 02
Write a function num_to_list/1
that takes a number and returns a string from 1 up to the number joined with commas, e.g:
num_to_list(10) #=> "1,2,3,4,5,6,7,8,9,10"
How about:
def num_to_list(n), do: 1..n |> Enum.join(",")
Problem 2 solution from elixirexperince.com