python3实现短网址和数字相互转换的方法

import mathimport decimaldef convert_to_code(num):  """  将数字转换为代码  """  def get_num(num, out=''):    num = decimal.Decimal(num)    codes = "abcdefghjkmnpqrstuvwxyz23456789ABCDEFGHJKMNPQRSTUVWXYZ"    if num > 53:      key = num % 54      num = math.floor(num / 54) - 1      return get_num(num, codes[int(key)] + out)    else:      return codes[int(num)] + out  return get_num(num)def convert_to_num(code):  """  将代码转为数字  """  import math  codes = "abcdefghjkmnpqrstuvwxyz23456789ABCDEFGHJKMNPQRSTUVWXYZ"  num = 0  num = decimal.Decimal(num)  i = len(code)  for char in code:    i -= 1    pos = codes.find(char)    num += (54 ** i) * (pos + 1)  num -= 1  # 任意数的 0 次方等于1，所以需要减去  return int(num)