SimplePie::merge_items( array $urls, int $start = 0, int $end = 0, int $limit = 0 ): array

3145    public static function merge_items($urls, $start = 0, $end = 0, $limit = 0)3146    {3147        if (is_array($urls) && sizeof($urls) > 0) {3148            $items = [];3149            foreach ($urls as $arg) {3150                if ($arg instanceof SimplePie) {3151                    $items = array_merge($items, $arg->get_items(0, $limit));3152                } else {3153                    trigger_error('Arguments must be SimplePie objects', E_USER_WARNING);3154                }3155            }3156 3157            usort($items, [get_class($urls[0]), 'sort_items']);3158 3159            if ($end === 0) {3160                return array_slice($items, $start);3161            }3162 3163            return array_slice($items, $start, $end);3164        }3165 3166        trigger_error('Cannot merge zero SimplePie objects', E_USER_WARNING);3167        return [];3168    }