<?phpnamespaceGuzzleHttp\Promise;interfaceTaskQueueInterface{/** * Returns true if the queue is empty. * * @return bool */publicfunctionisEmpty();/** * Adds a task to the queue that will be executed the next time run is * called. * * @param callable $task */publicfunctionadd(callable$task);/** * Execute all of the pending task in the queue. */publicfunctionrun();}