Pantheon\Terminus\Models\Environment::getParentEnvironment PHP Метод

    public function getParentEnvironment()
    {
        switch ($this->id) {
            case 'dev':
                return null;
            case 'live':
                $parent_env_id = 'test';
                break;
            case 'test':
            default:
                $parent_env_id = 'dev';
                break;
        }
        $environment = $this->getSite()->getEnvironments()->get($parent_env_id);
        return $environment;
    }