def get_feedback(self, block = True, timeout = None):
if self._feedback_greenlet is None:<EOL><INDENT>self._feedback_greenlet = gevent.spawn(self._feedback_loop)<EOL><DEDENT>return self._feedback_queue.get(block = block, timeout = timeout)<EOL>
Gets the next feedback message.

Each feedback message is a 2-tuple of (timestamp, device_token).