protected function formatSatisfies(array $specs)
    {
        $clauses = array_map(function ($clause) use ($specs) {
            if ($result = $this->formatClause($specs, $clause)) {
                return vsprintf('%s: %s', [
                    ucfirst(str_replace('_', ' ', $clause)),
                    $result,
                ]);
            }
        }, ['from', 'excluded_from', 'on', 'excluded_on', 'to', 'excluded_to']);

        return implode(PHP_EOL, array_filter($clauses));
    }