import base64

def safe_base64_decode(s):

if len(s) % 4 != 0:

s = s+'{}'.format('='*(4-len(s) % 4)) # 输入字符串的长度不是4的倍数,向上补足'='

# print(s)

else:

s

return base64.b64decode(s)

print(safe_base64_decode('YWJjZA=='), safe_base64_decode('YWJjZA'))