Simple turtle attack script

while true do
  while not redstone.getInput("back") do
    turtle.attack()
    while turtle.suck() do
    end
    for i=1,16 do
      if turtle.getItemCount(i) > 0
        turtle.select(i)
        turtle.dropDown()
      end
    end
    sleep(.1)
  end
  sleep(.3)
end