spiral_print.py

sp = [
  [1, 2, 3],
  [8, 9, 4],
  [7, 6, 5]
 ]


def rot90(m):
  return list(zip(*m))[::-1]

def spiral_print(m, acc):
  if len(m) == 0:
    acc = list(map(list, acc))
    print(sum(acc, []))
    return 'ok'
  else:
    acc.append(m[0])
    mn = list(zip(*m[1:]))[::-1]
    return spiral_print(mn, acc)


spiral_print(sp, [])