trim($x), $tags); foreach ($tags as $tag) { if (empty($tag)) { throw new VoteInvalidFormatException('found empty tag'); } } return $tags; } public static function getRankingAsString(array $ranking): string { foreach ($ranking as &$rank) { if (\is_array($rank)) { sort($rank); $rank = implode(' = ', $rank); } } return implode(' > ', $ranking); } }