code: def _send_msg(self, header, payload):
          
  
          if self.verbose:
              print('->', repr(header))
              print('..', repr(payload))
          assert header.payload == len(payload)
          try:
              sent = self.socket.send(header + payload)
          except IOError as err:
              raise ConnError(*err.args)
  
          # FIXME FIXME FIXME:
          # investigate under which situations socket.send should be retried
          # instead of aborted.
          # FIXME FIXME FIXME
          if sent < len(header + payload):
              raise ShortWrite(sent, len(header + payload))
          assert sent == len(header + payload), sent
docs: send message to server