public function render(OptionCollection $options)
    {
        # echo "* Available options:\n";
        $lines = array();
        foreach ($options as $option) {
            $c1 = $this->renderOption($option);
            $lines[] = "\t".$c1;
            $lines[] = wordwrap("\t\t".$option->desc, $this->screenWidth, "\n\t\t");  # wrap text
            $lines[] = '';
        }

        return implode("\n", $lines);
    }