function hanoi(n, start, end_, extra, move_disk)
  if n == 1 then
    move_disk(1, start, end_)
  else
    hanoi(n - 1, start, extra, end_, move_disk)
    move_disk(n, start, end_)
    hanoi(n - 1, extra, end_, start, move_disk)
  end
end

function print_instruction(disk, start, end_)
  print("Move disk #"..disk.." from "..start.." to "..end_)
end

hanoi(3, "a", "c", "b", print_instruction)