Kraken\Event\BaseEventEmitterTrait::attachOnceListener PHP Method

    protected function attachOnceListener($pointer, $event, callable $listener)
    {
        $emitter = $this;
        return function () use($emitter, $listener, $event, $pointer) {
            unset($emitter->eventListeners[$event][$pointer]);
            return call_user_func_array($listener, func_get_args());
        };
    }