-- Homework 26, challenge: Stack.
--
-- Build a `stack` table with:
--   stack.items       -- list
--   stack:push(v)     -- adds v on top
--   stack:pop()       -- removes and returns the top
--   stack:peek()      -- returns the top without removing (or nil)
--   stack:size()      -- returns the number of items
--
-- Push three values, then call size, peek, pop, pop, size in order
-- and print the results.
--
-- Run with: lua exercises/26/homework/04-stack.lua

-- Your code goes here: