python报如下错误，请问怎么解决？
Traceback (most recent call last):
File "<string>", line 1, in <module>
File "/Library/Python/2.6/site-packages/pyotp/totp.py", line 44, in now
return self.generate_otp(self.timecode(datetime.datetime.now()))
File "/Library/Python/2.6/site-packages/pyotp/otp.py", line 33, in generate_otp
hasher = hmac.new(self.byte_secret(), self.int_to_bytestring(input), self.digest)
File "/Library/Python/2.6/site-packages/pyotp/otp.py", line 50, in byte_secret
return base64.b32decode(self.secret, casefold=True)
File "/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/base64.py", line 222, in b32decode
raise TypeError('Non-base32 digit found')
TypeError: Non-base32 digit found
