GraphQL\Utils::groupBy PHP Méthode

    public static function groupBy($traversable, callable $keyFn)
    {
        self::invariant(is_array($traversable) || $traversable instanceof \Traversable, __METHOD__ . ' expects array or Traversable');
        $grouped = [];
        foreach ($traversable as $key => $value) {
            $newKeys = (array) $keyFn($value, $key);
            foreach ($newKeys as $key) {
                $grouped[$key][] = $value;
            }
        }
        return $grouped;
    }