python3实现短网址和数字相互转换的方法

import math
import decimal
def 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)