code: def success(self):
          
          return self.ack.upper() in (self.config.ACK_SUCCESS,
                                      self.config.ACK_SUCCESS_WITH_WARNING)
docs: Checks for the presence of errors in the response. Returns ``True`` if
          all is well, ``False`` otherwise.
  
          :rtype: bool
          :returns ``True`` if PayPal says our query was successful.