private function insertNewFileFunctions(iterable $new): void
    {
        // early return when there is nothing to be added
        if (0 === \count($new)) {
            return;
        }
        $table = $this->getTable();
        $db    = $this->getDb();

        foreach ($new as $file_function => $data) {
            $query      = $db->prepare(
                "INSERT INTO $table (function, added_at, changed_at) VALUES (:file_function, NOW(), :changed_at)"
            );
            $changed_at = $data->getChangedAt();
            $query->bindParam(":file_function", $file_function);
            $query->bindParam(":changed_at", $changed_at);
            $query->execute();
        }
    }