Love2D code for seeing what key/joystick button is pressed

Love2D_KeyTest.lua

game = {}
game.button= ""
game.key = ""

function love.load()
  success = love.graphics.setMode(320, 240, false, 0)
end

function love.update(dt)
end

function love.draw()
  love.graphics.clear()
  love.graphics.printf(game.button, 0, 0, 50, "left")
  love.graphics.printf(game.key, 0, 50, 50, "left") 
end

function love.joystickreleased(joystick, button)
  game.button = button
end

function love.keyreleased(key)
  game.key = key
end