生成一个随机验证码

# 数字/数字+字母
# def rand_code(n=6 , alph_flag = True):
#     code = ''
#     for i in range(n):
#         rand_num = str(random.randint(0,9))
#         if alph_flag:
#             rand_alph = chr(random.randint(97,122))
#             rand_alph_upper = chr(random.randint(65,90))
#             rand_num = random.choice([rand_num,rand_alph,rand_alph_upper])
#         code += rand_num
#     return code
#
# ret = rand_code(n = 4)
# print(ret)