code: def _send_output(self, message_body=None):
          
          self._buffer.extend((bytes(b""), bytes(b"")))
          msg = bytes(b"\r\n").join(self._buffer)
          del self._buffer[:]
          # If msg and message_body are sent in a single send() call,
          # it will avoid performance problems caused by the interaction
          # between delayed ack and the Nagle algorithm.
          if isinstance(message_body, bytes):
              msg += message_body
              message_body = None
          self.send(msg)
          if message_body is not None:
              # message_body was not a string (i.e. it is a file), and
              # we must run the risk of Nagle.
              self.send(message_body)
docs: Send the currently buffered request and clear the buffer.
  
          Appends an extra \\r\\n to the buffer.
          A message_body may be specified, to be appended to the request.