private function prepareOptions($options, $forceOptions = [])
    {
        $optionString = '';

        foreach ($forceOptions as $option => $value) {
            if (is_numeric($option)) {
                $options[$value] = null;
            } else {
                $options[$option] = $value;
            }
        }

        foreach ($options as $option => $value) {

            if (is_null($value)) {
                $optionString .= ' ' . $option;
            } else {
                $optionString .= ' ' . $option . '=' . $value;
            }
        }

        return $optionString;
    }