def request(self, method, args, response_cb):
request_id = self._next_request_id<EOL>self._next_request_id = request_id + <NUM_LIT:1><EOL>self._msgpack_stream.send([<NUM_LIT:0>, request_id, method, args])<EOL>self._pending_requests[request_id] = response_cb<EOL>
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.