protected function formatVariables($key, array $values)
    {
        switch ($key) {
            case 'PHP_PECL':
                return $this->formatPeclPackages($values);
            case 'PHP_COMMANDS':
                return $this->formatRunCommand($values);
            case 'PHP_EXT_CONFIG':
            case 'PHP_EXT_ENABLE':
            case 'PHP_EXT_INSTALL':
            case 'PACKAGE_INSTALL':
                return $this->formatValueDelimiter($values);
        }
    }