public function setSort($fieldName, $order = 'asc'): self
    {
        if (null !== $fieldName) {
            $sort = [];
            $fields = is_array($fieldName) ? $fieldName : [$fieldName => $order];

            foreach ($fields as $fieldName => $order) {
                $sort[] = [$fieldName => $order];
            }
        } else {
            $sort = null;
        }

        $this->sort = $sort;

        return $this;
    }