code: def _build_message_body(self, body_size):
          
          body = bytes()
          while len(body) < body_size:
              if not self._inbound:
                  self.check_for_errors()
                  sleep(IDLE_WAIT)
                  continue
              body_piece = self._inbound.pop(0)
              if not body_piece.value:
                  break
              body += body_piece.value
          return body
docs: Build the Message body from the inbound queue.
  
          :rtype: str