code: def request(self, method, args, response_cb):
          
          request_id = self._next_request_id
          self._next_request_id = request_id + 1
          self._msgpack_stream.send([0, request_id, method, args])
          self._pending_requests[request_id] = response_cb
docs: Send a msgpack-rpc request to Nvim.
  
          A msgpack-rpc with method `method` and argument `args` is sent to
          Nvim. The `response_cb` function is called with when the response
          is available.