code: def __handle_low_seq_resend(self, msg, req):
          
          if msg[M_TYPE] == E_FAILED and msg[M_PAYLOAD][P_CODE] == E_FAILED_CODE_LOWSEQNUM:
              with self.__seqnum_lock:
                  self.__seqnum = int(msg[M_PAYLOAD][P_MESSAGE])
              # return value indicating shutdown not useful here since this is run in receiver thread
              self.__retry_enqueue(PreparedMessage(req._inner_msg_out, req.id_))
              return True
          return False
docs: special error case - low sequence number (update sequence number & resend if applicable). Returns True if
             a resend was scheduled, False otherwise. MUST be called within self.__requests lock.