-- Homework 25, challenge: build this string_utils module.
--
-- Expose at least three functions of your own design. Suggestions:
--   M.shout(s)           -- s in upper case with "!" appended
--   M.echo(s, n)         -- s repeated n times with spaces between
--   M.reverse_words(s)   -- words of s in reverse order
--
-- The third one is a stretch. Pick something simpler if needed.

local M = {}

-- Your functions go here:


-- TODO: return M