code: def checkPassword(self, password):
          
          if isinstance(password, unicode):
              password = password.encode('utf-8')
          correctResponse = _calcResponse(self.challenge, self.nonce, password)
          return correctResponse == self.response
docs: Check the given plaintext password against the response in this
          credentials object.
  
          @type password: C{str}
          @param password: The known correct password associated with
              C{self.username}.
  
          @return: A C{bool}, C{True} if this credentials object agrees with the
              given password, C{False} otherwise.