public function getRefreshableFoos($hour) {
        // not completely convinced hour will always be an int. let's be sure.
        $hour = (int)$hour;
        $sql = 'SELECT blah, blih, bloh FROM foos';
        $stmt = $this->pdo->query($sql);
        $rows = $stmt->fetchAll(PDO::FETCH_GROUP | PDO::FETCH_UNIQUE);
        $refreshables = [];
        foreach ($rows as $id=> $row) {
            if ($hour === 0)
            {
                $hour = 24;
            }
            if ($codePRS % 24 === $hour) {
                $refreshables[$id] = $row;
            }
        }
        return $refreshables;
    }